Heat
(a) Degree of hotness or coldness ✅
(b) Amount of heat
(c) Pressure
(d) None
Explanation: Temperature indicates thermal state, not total heat.
Q2. SI unit of temperature is:
(a) Kelvin ✅
(b) Celsius
(c) Fahrenheit
(d) None
Explanation: Kelvin is the absolute SI unit.
Q3. Celsius scale is based on:
(a) Ice point 0°C and steam point 100°C ✅
(b) Ice point 32°C and steam point 212°C
(c) Absolute zero
(d) None
Explanation: Standard Celsius scale.
Q4. Fahrenheit scale is based on:
(a) Ice point 32°F and steam point 212°F ✅
(b) Ice point 0°F and steam point 100°F
(c) Absolute zero
(d) None
Explanation: Standard Fahrenheit scale.
Q5. Relation between Celsius and Fahrenheit is:
(a) C/5 = (F – 32)/9 ✅
(b) C/9 = (F – 32)/5
(c) C = F
(d) None
Explanation: Conversion formula.
Q6. Relation between Celsius and Kelvin is:
(a) K = C + 273 ✅
(b) K = C – 273
(c) K = C × 273
(d) None
Explanation: Absolute scale relation.
Q7. Absolute zero is:
(a) 0 K ✅
(b) 0°C
(c) –273°C
(d) None
Explanation: Lowest possible temperature.
Q8. Absolute zero in Celsius is:
(a) –273°C ✅
(b) 0°C
(c) 100°C
(d) None
Explanation: Equivalent to 0 K.
Q9. Absolute zero in Fahrenheit is:
(a) –460°F ✅
(b) 0°F
(c) 32°F
(d) None
Explanation: Equivalent to 0 K.
Q10. Thermometer measures:
(a) Temperature ✅
(b) Pressure
(c) Density
(d) None
Explanation: Device for temperature.
Q11. Mercury thermometer works on:
(a) Expansion of mercury ✅
(b) Expansion of alcohol
(c) Pressure
(d) None
Explanation: Mercury expands with heat.
Q12. Alcohol thermometer is used for:
(a) Low temperatures ✅
(b) High temperatures
(c) Pressure
(d) None
Explanation: Alcohol expands more, suitable for cold regions.
Q13. Clinical thermometer range is:
(a) 35°C to 42°C ✅
(b) 0°C to 100°C
(c) –10°C to 50°C
(d) None
Explanation: Human body temperature range.
Q14. Normal human body temperature is:
(a) 37°C ✅
(b) 36°C
(c) 38°C
(d) None
Explanation: Standard value.
Q15. Thermocouple works on:
(a) Seebeck effect ✅
(b) Joule effect
(c) Expansion
(d) None
Explanation: Voltage produced by temperature difference.
Q16. Pyrometer measures:
(a) Very high temperatures ✅
(b) Low temperatures
(c) Pressure
(d) None
Explanation: Used in furnaces.
Q17. Gas thermometer is based on:
(a) Pressure variation with temperature ✅
(b) Expansion of mercury
(c) Expansion of alcohol
(d) None
Explanation: Gas laws.
Q18. Resistance thermometer works on:
(a) Change in resistance with temperature ✅
(b) Expansion
(c) Pressure
(d) None
Explanation: Metals change resistance with heat.
Q19. Kelvin scale is also called:
(a) Absolute scale ✅
(b) Celsius scale
(c) Fahrenheit scale
(d) None
Explanation: Starts from absolute zero.
Q20. Triple point of water is:
(a) 273.16 K ✅
(b) 273 K
(c) 0°C
(d) None
Explanation: Standard fixed point.
Q21. Temperature is a:
(a) Scalar quantity ✅
(b) Vector quantity
(c) Tensor quantity
(d) None
Explanation: Has magnitude only.
Q22. Heat and temperature are:
(a) Different concepts ✅
(b) Same
(c) Identical
(d) None
Explanation: Heat is energy, temperature is measure.
Q23. Temperature can be measured in:
(a) Celsius, Fahrenheit, Kelvin ✅
(b) Joule, Watt, Pascal
(c) Newton, Joule, Watt
(d) None
Explanation: Standard scales.
Q24. Conversion from Celsius to Kelvin:
(a) K = C + 273 ✅
(b) K = C – 273
(c) K = C × 273
(d) None
Explanation: Absolute relation.
Q25. Conversion from Celsius to Fahrenheit:
(a) F = (9/5)C + 32 ✅
(b) F = (5/9)C + 32
(c) F = C – 32
(d) None
Explanation: Standard formula.
Q26. Conversion from Fahrenheit to Celsius:
(a) C = (5/9)(F – 32) ✅
(b) C = (9/5)(F – 32)
(c) C = F + 32
(d) None
Explanation: Standard formula.
Q27. Conversion from Kelvin to Celsius:
(a) C = K – 273 ✅
(b) C = K + 273
(c) C = K × 273
(d) None
Explanation: Absolute relation.
Q28. Conversion from Kelvin to Fahrenheit:
(a) F = (9/5)(K – 273) + 32 ✅
(b) F = (5/9)(K – 273) + 32
(c) F = K – 32
(d) None
Explanation: Standard formula.
Q29. Temperature is measured using:
(a) Thermometers ✅
(b) Barometers
(c) Manometers
(d) None
Explanation: Thermometers are standard devices.
Q30. Thermodynamic temperature scale is:
(a) Kelvin ✅
(b) Celsius
(c) Fahrenheit
(d) None
Explanation: Based on absolute zero.
Q31. Heat is a form of:
(a) Energy ✅
(b) Pressure
(c) Force
(d) None
Explanation: Heat is thermal energy in transit.
Q32. SI unit of heat is:
(a) Joule ✅
(b) Calorie
(c) Watt
(d) None
Explanation: Heat is energy, measured in joules.
Q33. 1 calorie =
(a) 4.2 J ✅
(b) 1 J
(c) 10 J
(d) None
Explanation: Standard conversion.
Q34. Heat transfer occurs from:
(a) Higher temperature to lower temperature ✅
(b) Lower to higher
(c) Equal temperatures
(d) None
Explanation: Heat flows spontaneously from hot to cold.
Q35. Modes of heat transfer are:
(a) Conduction, convection, radiation ✅
(b) Pressure, density, volume
(c) Magnetism, electricity, gravity
(d) None
Explanation: Three main processes.
Q36. Conduction occurs in:
(a) Solids ✅
(b) Liquids
(c) Gases
(d) None
Explanation: Heat transfer by molecular vibration.
Q37. Convection occurs in:
(a) Liquids and gases ✅
(b) Solids
(c) Vacuum
(d) None
Explanation: Heat transfer by bulk motion.
Q38. Radiation occurs in:
(a) Vacuum ✅
(b) Solids
(c) Liquids
(d) None
Explanation: Heat transfer without medium.
Q39. Good conductor of heat is:
(a) Metal ✅
(b) Wood
(c) Plastic
(d) None
Explanation: Metals have free electrons.
Q40. Poor conductor of heat is:
(a) Wood ✅
(b) Copper
(c) Aluminium
(d) None
Explanation: Wood is insulator.
Q41. Thermal conductivity is property of:
(a) Material to conduct heat ✅
(b) Material to resist heat
(c) Material to store heat
(d) None
Explanation: k = QL / (AΔTt).
Q42. Unit of thermal conductivity is:
(a) W/m·K ✅
(b) J/kg·K
(c) N/m²
(d) None
Explanation: SI unit.
Q43. Heat conduction rate depends on:
(a) Area, thickness, temperature difference ✅
(b) Mass only
(c) Pressure only
(d) None
Explanation: Fourier’s law.
Q44. Fourier’s law states:
(a) Q/t ∝ ΔT/L ✅
(b) Q ∝ ΔT
(c) Q ∝ L
(d) None
Explanation: Heat flow proportional to gradient.
Q45. Convection current is due to:
(a) Density difference ✅
(b) Pressure difference
(c) Gravity only
(d) None
Explanation: Hot fluid rises, cold sinks.
Q46. Sea breeze is example of:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Air circulation due to heating.
Q47. Land breeze occurs:
(a) At night ✅
(b) At day
(c) Always
(d) None
Explanation: Land cools faster at night.
Q48. Radiation is transfer of heat by:
(a) Electromagnetic waves ✅
(b) Conduction
(c) Convection
(d) None
Explanation: Infrared radiation.
Q49. Radiation does not require:
(a) Medium ✅
(b) Solid
(c) Liquid
(d) Gas
Explanation: Can occur in vacuum.
Q50. Black body absorbs:
(a) All radiation ✅
(b) Some radiation
(c) No radiation
(d) None
Explanation: Perfect absorber.
Q51. Black body emits:
(a) Maximum radiation ✅
(b) Minimum radiation
(c) No radiation
(d) None
Explanation: Perfect emitter.
Q52. Stefan–Boltzmann law states:
(a) E ∝ T⁴ ✅
(b) E ∝ T²
(c) E ∝ T
(d) None
Explanation: Radiant energy ∝ fourth power of temperature.
Q53. Unit of Stefan–Boltzmann constant is:
(a) W/m²·K⁴ ✅
(b) J/kg·K
(c) N/m²
(d) None
Explanation: SI unit.
Q54. Wien’s displacement law states:
(a) λmax T = constant ✅
(b) λmax ∝ T
(c) λmax ∝ 1/T²
(d) None
Explanation: Peak wavelength inversely proportional to temperature.
Q55. Greenhouse effect is due to:
(a) Trapping of infrared radiation ✅
(b) Trapping of UV radiation
(c) Trapping of visible light
(d) None
Explanation: CO₂ and gases trap heat.
Q56. Good absorber is also:
(a) Good emitter ✅
(b) Poor emitter
(c) Insulator
(d) None
Explanation: Kirchhoff’s law.
Q57. Shiny surfaces are:
(a) Poor absorbers and emitters ✅
(b) Good absorbers
(c) Good emitters
(d) None
Explanation: Reflect radiation.
Q58. Black surfaces are:
(a) Good absorbers and emitters ✅
(b) Poor absorbers
(c) Poor emitters
(d) None
Explanation: Absorb and emit strongly.
Q59. Radiation depends on:
(a) Surface area and temperature ✅
(b) Mass
(c) Pressure
(d) None
Explanation: Larger area → more radiation.
Q60. Heat conduction is fastest in:
(a) Metals ✅
(b) Wood
(c) Plastic
(d) None
Explanation: Free electrons carry energy.
Q61. Heat conduction is slowest in:
(a) Gases ✅
(b) Metals
(c) Liquids
(d) None
Explanation: Molecules far apart.
Q62. Thermal conductivity of silver is:
(a) Very high ✅
(b) Very low
(c) Moderate
(d) None
Explanation: Best conductor.
Q63. Thermal conductivity of wood is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Insulator.
Q64. Radiation from sun reaches earth by:
(a) Radiation ✅
(b) Conduction
(c) Convection
(d) None
Explanation: Space is vacuum.
Q65. Heat transfer in solids mainly by:
(a) Conduction ✅
(b) Convection
(c) Radiation
(d) None
Explanation: Molecules vibrate.
Q66. Heat transfer in liquids mainly by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Bulk motion.
Q67. Heat transfer in gases mainly by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Bulk motion.
Q68. Heat transfer in vacuum mainly by:
(a) Radiation ✅
(b) Conduction
(c) Convection
(d) None
Explanation: No medium.
Q69. Thermal radiation is mainly:
(a) Infrared ✅
(b) Ultraviolet
(c) Visible
(d) None
Explanation: Heat waves are infrared.
Q70. Radiation increases with:
(a) Temperature ✅
(b) Pressure
(c) Volume
(d) None
Explanation: Higher temperature → more radiation.
Q71. Thermal expansion is:
(a) Increase in size with rise in temperature ✅
(b) Decrease in size
(c) Constant size
(d) None
Explanation: Substances expand when heated.
Q72. Types of thermal expansion are:
(a) Linear, area, volume ✅
(b) Pressure, density, mass
(c) Length, width, height
(d) None
Explanation: Three main types.
Q73. Linear expansion occurs in:
(a) Length ✅
(b) Area
(c) Volume
(d) None
Explanation: Increase in length.
Q74. Areal expansion occurs in:
(a) Surface area ✅
(b) Length
(c) Volume
(d) None
Explanation: Increase in area.
Q75. Cubical expansion occurs in:
(a) Volume ✅
(b) Length
(c) Area
(d) None
Explanation: Increase in volume.
Q76. Coefficient of linear expansion is:
(a) ΔL / (LΔT) ✅
(b) ΔA / (AΔT)
(c) ΔV / (VΔT)
(d) None
Explanation: Ratio of length change to temperature change.
Q77. Unit of coefficient of linear expansion is:
(a) K⁻¹ ✅
(b) J/K
(c) N/m²
(d) None
Explanation: Reciprocal of temperature.
Q78. Coefficient of area expansion is:
(a) ΔA / (AΔT) ✅
(b) ΔL / (LΔT)
(c) ΔV / (VΔT)
(d) None
Explanation: Ratio of area change to temperature change.
Q79. Coefficient of volume expansion is:
(a) ΔV / (VΔT) ✅
(b) ΔL / (LΔT)
(c) ΔA / (AΔT)
(d) None
Explanation: Ratio of volume change to temperature change.
Q80. Relation between coefficients is:
(a) β ≈ 2α, γ ≈ 3α ✅
(b) β = α, γ = α
(c) β = 3α, γ = 2α
(d) None
Explanation: Area ≈ 2× linear, volume ≈ 3× linear.
Q81. Expansion of solids is:
(a) Least ✅
(b) Greatest
(c) Moderate
(d) None
Explanation: Solids expand less.
Q82. Expansion of liquids is:
(a) More than solids ✅
(b) Less than solids
(c) Same
(d) None
Explanation: Liquids expand more.
Q83. Expansion of gases is:
(a) Greatest ✅
(b) Least
(c) Same
(d) None
Explanation: Gases expand most.
Q84. Anomalous expansion of water occurs between:
(a) 0°C and 4°C ✅
(b) 4°C and 10°C
(c) 10°C and 20°C
(d) None
Explanation: Water contracts on heating from 0°C to 4°C.
Q85. Density of water is maximum at:
(a) 4°C ✅
(b) 0°C
(c) 10°C
(d) None
Explanation: Due to anomalous expansion.
Q86. Railway tracks are laid with:
(a) Gaps ✅
(b) No gaps
(c) Overlap
(d) None
Explanation: To allow expansion.
Q87. Telephone wires sag in:
(a) Summer ✅
(b) Winter
(c) Rainy season
(d) None
Explanation: Expansion in heat.
Q88. Telephone wires tighten in:
(a) Winter ✅
(b) Summer
(c) Rainy season
(d) None
Explanation: Contraction in cold.
Q89. Bimetallic strip works on:
(a) Different expansion of metals ✅
(b) Same expansion
(c) No expansion
(d) None
Explanation: Used in thermostats.
Q90. Expansion joints are used in:
(a) Bridges ✅
(b) Houses
(c) Cars
(d) None
Explanation: To allow expansion.
Q91. Glass cracks when heated suddenly because:
(a) Unequal expansion ✅
(b) Equal expansion
(c) No expansion
(d) None
Explanation: Different parts expand differently.
Q92. Liquids expand more than solids because:
(a) Molecules are loosely packed ✅
(b) Molecules are tightly packed
(c) Molecules fixed
(d) None
Explanation: Looser bonding.
Q93. Gases expand most because:
(a) Molecules are far apart ✅
(b) Molecules are close
(c) Molecules fixed
(d) None
Explanation: Large freedom of motion.
Q94. Anomalous expansion of water helps:
(a) Aquatic life in winter ✅
(b) Plants
(c) Birds
(d) None
Explanation: Ice floats, water below remains at 4°C.
Q95. Expansion of solids is used in:
(a) Thermometers ✅
(b) Hydrometers
(c) Manometers
(d) None
Explanation: Mercury expands in thermometer.
Q96. Expansion of liquids is used in:
(a) Thermometers ✅
(b) Hydrometers
(c) Manometers
(d) None
Explanation: Alcohol expands in thermometer.
Q97. Expansion of gases is used in:
(a) Hot air balloons ✅
(b) Hydrometers
(c) Manometers
(d) None
Explanation: Heated air expands, balloon rises.
Q98. Coefficient of expansion depends on:
(a) Material ✅
(b) Shape
(c) Area
(d) None
Explanation: Each material has unique coefficient.
Q99. Expansion is proportional to:
(a) Original dimension and temperature change ✅
(b) Pressure
(c) Mass
(d) None
Explanation: ΔL ∝ LΔT.
Q100. Expansion is prevented by:
(a) Cooling ✅
(b) Heating
(c) Pressure
(d) None
Explanation: Lower temperature reduces expansion.
Q101. Convection is heat transfer by:
(a) Bulk movement of fluid ✅
(b) Vibration of molecules
(c) Electromagnetic waves
(d) None
Explanation: Fluid particles move carrying heat.
Q102. Convection occurs in:
(a) Liquids and gases ✅
(b) Solids
(c) Vacuum
(d) None
Explanation: Requires fluid motion.
Q103. Natural convection occurs due to:
(a) Density differences ✅
(b) Pressure differences
(c) Gravity only
(d) None
Explanation: Hot fluid rises, cold sinks.
Q104. Forced convection occurs due to:
(a) External agency like fan/pump ✅
(b) Density difference
(c) Gravity
(d) None
Explanation: Fluid motion is forced.
Q105. Sea breeze is example of:
(a) Natural convection ✅
(b) Forced convection
(c) Conduction
(d) None
Explanation: Air circulation due to heating.
Q106. Land breeze occurs:
(a) At night ✅
(b) At day
(c) Always
(d) None
Explanation: Land cools faster at night.
Q107. Convection currents in atmosphere cause:
(a) Winds ✅
(b) Rain
(c) Snow
(d) None
Explanation: Air circulation.
Q108. Convection currents in oceans cause:
(a) Ocean currents ✅
(b) Waves
(c) Tides
(d) None
Explanation: Water circulation.
Q109. Convection currents in earth’s mantle cause:
(a) Plate movements ✅
(b) Winds
(c) Rain
(d) None
Explanation: Responsible for continental drift.
Q110. Convection currents in sun cause:
(a) Solar phenomena ✅
(b) Rain
(c) Snow
(d) None
Explanation: Energy transport.
Q111. Convection is faster in:
(a) Liquids ✅
(b) Solids
(c) Vacuum
(d) None
Explanation: Bulk motion easier.
Q112. Convection is slower in:
(a) Gases ✅
(b) Liquids
(c) Solids
(d) None
Explanation: Less dense medium.
Q113. Convection cannot occur in:
(a) Solids ✅
(b) Liquids
(c) Gases
(d) None
Explanation: Molecules fixed.
Q114. Heating of water in vessel occurs by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Hot water rises, cold sinks.
Q115. Heating of air in room by heater occurs by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Air circulates.
Q116. Convection currents are important in:
(a) Weather phenomena ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause winds, rains.
Q117. Convection currents are important in:
(a) Ocean circulation ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause ocean currents.
Q118. Convection currents are important in:
(a) Earth’s interior ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause plate tectonics.
Q119. Convection currents are important in:
(a) Sun ✅
(b) Moon
(c) Earth’s crust only
(d) None
Explanation: Energy transport.
Q120. Convection is useful in:
(a) Heating and cooling systems ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Used in air conditioners, geysers.
Q121. Conductor is a material that:
(a) Allows heat to pass easily ✅
(b) Blocks heat
(c) Stores heat
(d) None
Explanation: Metals are good conductors.
Q122. Insulator is a material that:
(a) Does not allow heat to pass easily ✅
(b) Allows heat freely
(c) Stores heat
(d) None
Explanation: Wood, plastic are insulators.
Q123. Good conductors of heat are:
(a) Metals ✅
(b) Wood
(c) Plastic
(d) None
Explanation: Free electrons carry heat.
Q124. Poor conductors of heat are:
(a) Non‑metals ✅
(b) Metals
(c) Alloys
(d) None
Explanation: Non‑metals lack free electrons.
Q125. Example of good conductor:
(a) Copper ✅
(b) Wood
(c) Plastic
(d) None
Explanation: Copper conducts heat well.
Q126. Example of poor conductor:
(a) Wood ✅
(b) Copper
(c) Aluminium
(d) None
Explanation: Wood resists heat flow.
Q127. Example of insulator:
(a) Plastic ✅
(b) Iron
(c) Silver
(d) None
Explanation: Plastic blocks heat transfer.
Q128. Silver is:
(a) Best conductor of heat ✅
(b) Poor conductor
(c) Insulator
(d) None
Explanation: Silver has highest thermal conductivity.
Q129. Thermal conductivity of metals is:
(a) High ✅
(b) Low
(c) Zero
(d) None
Explanation: Metals conduct heat well.
Q130. Thermal conductivity of wood is:
(a) Low ✅
(b) High
(c) Zero
(d) None
Explanation: Wood is insulator.
Q131. Thermal conductivity of glass is:
(a) Low ✅
(b) High
(c) Zero
(d) None
Explanation: Glass is poor conductor.
Q132. Thermal conductivity of rubber is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Rubber is insulator.
Q133. Thermal conductivity of diamond is:
(a) Very high ✅
(b) Very low
(c) Moderate
(d) None
Explanation: Diamond conducts heat extremely well.
Q134. Thermal conductivity of air is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Air is poor conductor.
Q135. Wool keeps us warm because:
(a) Traps air ✅
(b) Conducts heat
(c) Reflects heat
(d) None
Explanation: Air is poor conductor.
Q136. Thermos flask works on:
(a) Poor conduction, convection, radiation ✅
(b) Good conduction
(c) Good convection
(d) None
Explanation: Prevents heat loss.
Q137. Cooking utensils are made of:
(a) Good conductors ✅
(b) Poor conductors
(c) Insulators
(d) None
Explanation: Metals conduct heat quickly.
Q138. Handles of cooking utensils are made of:
(a) Insulators ✅
(b) Conductors
(c) Metals
(d) None
Explanation: Wood/plastic prevent burns.
Q139. Houses in cold regions are insulated with:
(a) Poor conductors ✅
(b) Good conductors
(c) Metals
(d) None
Explanation: Prevents heat loss.
Q140. Houses in hot regions use:
(a) Poor conductors ✅
(b) Good conductors
(c) Metals
(d) None
Explanation: Prevents heat gain.
Q141. Blankets keep us warm because:
(a) Trap air ✅
(b) Conduct heat
(c) Reflect heat
(d) None
Explanation: Air is poor conductor.
Q142. Double‑walled glass keeps liquid hot because:
(a) Air gap acts as insulator ✅
(b) Conducts heat
(c) Reflects heat
(d) None
Explanation: Prevents heat transfer.
Q143. Refrigerator walls are made of:
(a) Insulating material ✅
(b) Conducting material
(c) Metals
(d) None
Explanation: Prevents heat entry.
Q144. Ice box is made of:
(a) Insulating material ✅
(b) Conducting material
(c) Metals
(d) None
Explanation: Prevents heat entry.
Q145. Thermal insulators are used in:
(a) Building construction ✅
(b) Cooking utensils
(c) Electrical wires
(d) None
Explanation: Prevent heat transfer.
Q146. Good conductors are used in:
(a) Cooking utensils ✅
(b) Blankets
(c) Wool
(d) None
Explanation: Metals transfer heat quickly.
Q147. Poor conductors are used in:
(a) Handles of utensils ✅
(b) Cooking pans
(c) Wires
(d) None
Explanation: Prevent burns.
Q148. Insulators are used in:
(a) Thermos flasks ✅
(b) Cooking utensils
(c) Metals
(d) None
Explanation: Prevent heat loss.
Q149. Metals feel cold to touch because:
(a) Conduct heat away quickly ✅
(b) Poor conductors
(c) Insulators
(d) None
Explanation: Heat flows rapidly from hand.
Q150. Woollen clothes keep us warm because:
(a) Trap air, a poor conductor ✅
(b) Conduct heat
(c) Reflect heat
(d) None
Explanation: Air prevents heat loss.
Q151. Thermodynamics is study of:
(a) Heat and work ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Deals with energy transformations.
Q152. Zeroth law of thermodynamics states:
(a) If A = B and B = C, then A = C ✅
(b) Energy is conserved
(c) Entropy increases
(d) None
Explanation: Basis of temperature measurement.
Q153. First law of thermodynamics states:
(a) Energy can neither be created nor destroyed ✅
(b) Entropy increases
(c) Energy is lost
(d) None
Explanation: Conservation of energy.
Q154. First law equation is:
(a) ΔQ = ΔU + ΔW ✅
(b) ΔQ = ΔU – ΔW
(c) ΔQ = ΔW
(d) None
Explanation: Heat supplied = internal energy + work.
Q155. Second law of thermodynamics states:
(a) Heat cannot flow from cold to hot spontaneously ✅
(b) Energy is conserved
(c) Entropy decreases
(d) None
Explanation: Direction of heat flow.
Q156. Second law also states:
(a) No engine is 100% efficient ✅
(b) Energy is conserved
(c) Work = heat
(d) None
Explanation: Some energy lost as waste.
Q157. Third law of thermodynamics states:
(a) Entropy at 0 K is minimum ✅
(b) Energy is conserved
(c) Heat flows hot to cold
(d) None
Explanation: Entropy tends to zero at absolute zero.
Q158. Internal energy depends on:
(a) Temperature ✅
(b) Pressure
(c) Volume
(d) None
Explanation: U ∝ T.
Q159. Work done in isothermal process is:
(a) W = nRT ln(V₂/V₁) ✅
(b) W = PΔV
(c) W = ΔU
(d) None
Explanation: Temperature constant.
Q160. Work done in adiabatic process is:
(a) W = (P₁V₁ – P₂V₂)/(γ – 1) ✅
(b) W = nRT ln(V₂/V₁)
(c) W = ΔU
(d) None
Explanation: No heat exchange.
Q161. Isothermal process means:
(a) Temperature constant ✅
(b) Pressure constant
(c) Volume constant
(d) None
Explanation: Heat exchange occurs.
Q162. Adiabatic process means:
(a) No heat exchange ✅
(b) Temperature constant
(c) Pressure constant
(d) None
Explanation: Q = 0.
Q163. Isochoric process means:
(a) Volume constant ✅
(b) Pressure constant
(c) Temperature constant
(d) None
Explanation: ΔV = 0.
Q164. Isobaric process means:
(a) Pressure constant ✅
(b) Volume constant
(c) Temperature constant
(d) None
Explanation: ΔP = 0.
Q165. Carnot cycle is:
(a) Ideal heat engine cycle ✅
(b) Real engine cycle
(c) Refrigerator cycle
(d) None
Explanation: Maximum efficiency.
Q166. Efficiency of Carnot engine is:
(a) η = 1 – T₂/T₁ ✅
(b) η = T₂/T₁
(c) η = T₁/T₂
(d) None
Explanation: Depends on source and sink temperatures.
Q167. Efficiency of Carnot engine depends on:
(a) Temperatures of source and sink ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q168. No engine can be:
(a) 100% efficient ✅
(b) 50% efficient
(c) 75% efficient
(d) None
Explanation: Some energy lost.
Q169. Refrigerator works on:
(a) Second law of thermodynamics ✅
(b) First law
(c) Third law
(d) None
Explanation: Heat flows cold to hot with work.
Q170. Coefficient of performance (COP) of refrigerator is:
(a) COP = Q₂/W ✅
(b) COP = W/Q₂
(c) COP = Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q171. Heat engine converts:
(a) Heat into work ✅
(b) Work into heat
(c) Heat into electricity
(d) None
Explanation: Basic function.
Q172. Efficiency of heat engine is:
(a) η = W/Q₁ ✅
(b) η = Q₁/W
(c) η = Q₂/W
(d) None
Explanation: Work done / heat supplied.
Q173. Entropy is measure of:
(a) Disorder ✅
(b) Order
(c) Energy
(d) None
Explanation: Randomness of system.
Q174. Unit of entropy is:
(a) J/K ✅
(b) J
(c) N/m²
(d) None
Explanation: SI unit.
Q175. Entropy of isolated system:
(a) Always increases ✅
(b) Always decreases
(c) Remains constant
(d) None
Explanation: Second law.
Q176. Internal energy of ideal gas depends on:
(a) Temperature only ✅
(b) Pressure
(c) Volume
(d) None
Explanation: U ∝ T.
Q177. Work done in isochoric process is:
(a) Zero ✅
(b) Maximum
(c) Minimum
(d) None
Explanation: ΔV = 0 → W = 0.
Q178. Heat supplied in isochoric process:
(a) Increases internal energy only ✅
(b) Increases work only
(c) Increases both
(d) None
Explanation: No work done.
Q179. Work done in isobaric process is:
(a) W = PΔV ✅
(b) W = nRT ln(V₂/V₁)
(c) W = ΔU
(d) None
Explanation: Pressure constant.
Q180. Heat supplied in isobaric process:
(a) Increases internal energy + work ✅
(b) Increases work only
(c) Increases internal energy only
(d) None
Explanation: Both terms.
Q181. In isothermal process:
(a) ΔU = 0 ✅
(b) ΔU > 0
(c) ΔU < 0
(d) None
Explanation: Temperature constant.
Q182. In adiabatic process:
(a) Q = 0 ✅
(b) W = 0
(c) ΔU = 0
(d) None
Explanation: No heat exchange.
Q183. Efficiency of real engines is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses.
Q184. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q185. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q186. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q187. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q188. Carnot cycle consists of:
(a) Two isothermal + two adiabatic processes ✅
(b) Two isobaric + two isochoric
(c) Four isothermal
(d) None
Explanation: Ideal cycle.
Q189. Efficiency of Carnot engine increases if:
(a) Sink temperature decreases ✅
(b) Source temperature decreases
(c) Both increase
(d) None
Explanation: η = 1 – T₂/T₁.
Q190. Efficiency of Carnot engine increases if:
(a) Source temperature increases ✅
(b) Sink temperature increases
(c) Both decrease
(d) None
Explanation: η = 1 – T₂/T₁.
Q191. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q192. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar to refrigerator.
Q193. COP of heat pump is:
(a) COP = Q₁/W ✅
(b) COP = Q₂/W
(c) COP = W/Q₁
(d) None
Explanation: Heat delivered / work.
Q194. Efficiency of refrigerator is expressed as:
(a) COP ✅
(b) η
(c) ΔU
(d) None
Explanation: Coefficient of performance.
Q195. Entropy change ΔS is:
(a) ΔQ/T ✅
(b) ΔQ × T
(c) ΔQ – T
(d) None
Explanation: Definition.
Q196. Entropy of reversible process:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q197. Entropy of irreversible process:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q198. Heat engine efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q199. In reversible process:
(a) Efficiency is maximum ✅
(b) Efficiency is minimum
(c) Efficiency is zero
(d) None
Explanation: Reversible processes are ideal.
Q200. In irreversible process:
(a) Efficiency is less than reversible ✅
(b) Efficiency is maximum
(c) Efficiency is zero
(d) None
Explanation: Practical losses reduce efficiency.
Q201. Isochoric process means:
(a) Volume constant ✅
(b) Pressure constant
(c) Temperature constant
(d) None
Explanation: ΔV = 0.
Q202. Isobaric process means:
(a) Pressure constant ✅
(b) Volume constant
(c) Temperature constant
(d) None
Explanation: ΔP = 0.
Q203. Isothermal process means:
(a) Temperature constant ✅
(b) Pressure constant
(c) Volume constant
(d) None
Explanation: ΔT = 0.
Q204. Adiabatic process means:
(a) No heat exchange ✅
(b) Temperature constant
(c) Pressure constant
(d) None
Explanation: Q = 0.
Q205. Work done in isothermal process is:
(a) W = nRT ln(V₂/V₁) ✅
(b) W = PΔV
(c) W = ΔU
(d) None
Explanation: Derived from gas laws.
Q206. Work done in adiabatic process is:
(a) W = (P₁V₁ – P₂V₂)/(γ – 1) ✅
(b) W = nRT ln(V₂/V₁)
(c) W = ΔU
(d) None
Explanation: No heat exchange.
Q207. Internal energy of ideal gas depends on:
(a) Temperature only ✅
(b) Pressure
(c) Volume
(d) None
Explanation: U ∝ T.
Q208. Heat supplied in isochoric process:
(a) Increases internal energy only ✅
(b) Increases work only
(c) Increases both
(d) None
Explanation: No work done.
Q209. Heat supplied in isobaric process:
(a) Increases internal energy + work ✅
(b) Increases work only
(c) Increases internal energy only
(d) None
Explanation: Both terms.
Q210. Carnot cycle consists of:
(a) Two isothermal + two adiabatic processes ✅
(b) Two isobaric + two isochoric
(c) Four isothermal
(d) None
Explanation: Ideal cycle.
Q211. Efficiency of Carnot engine is:
(a) η = 1 – T₂/T₁ ✅
(b) η = T₂/T₁
(c) η = T₁/T₂
(d) None
Explanation: Depends on source and sink.
Q212. Efficiency of real engines is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses reduce efficiency.
Q213. Refrigerator works on:
(a) Second law of thermodynamics ✅
(b) First law
(c) Third law
(d) None
Explanation: Heat flows cold to hot with work.
Q214. COP of refrigerator is:
(a) COP = Q₂/W ✅
(b) COP = W/Q₂
(c) COP = Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q215. COP of heat pump is:
(a) COP = Q₁/W ✅
(b) COP = Q₂/W
(c) COP = W/Q₁
(d) None
Explanation: Heat delivered / work.
Q216. Entropy is measure of:
(a) Disorder ✅
(b) Order
(c) Energy
(d) None
Explanation: Randomness of system.
Q217. Unit of entropy is:
(a) J/K ✅
(b) J
(c) N/m²
(d) None
Explanation: SI unit.
Q218. Entropy of isolated system:
(a) Always increases ✅
(b) Always decreases
(c) Remains constant
(d) None
Explanation: Second law.
Q219. Entropy change ΔS is:
(a) ΔQ/T ✅
(b) ΔQ × T
(c) ΔQ – T
(d) None
Explanation: Definition.
Q220. Entropy of reversible process:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q221. Entropy of irreversible process:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q222. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q223. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q224. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q225. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q226. Efficiency of Carnot engine increases if:
(a) Sink temperature decreases ✅
(b) Source temperature decreases
(c) Both increase
(d) None
Explanation: η = 1 – T₂/T₁.
Q227. Efficiency of Carnot engine increases if:
(a) Source temperature increases ✅
(b) Sink temperature increases
(c) Both decrease
(d) None
Explanation: η = 1 – T₂/T₁.
Q228. Isochoric process work done is:
(a) Zero ✅
(b) Maximum
(c) Minimum
(d) None
Explanation: ΔV = 0 → W = 0.
Q229. Isobaric process work done is:
(a) W = PΔV ✅
(b) W = nRT ln(V₂/V₁)
(c) W = ΔU
(d) None
Explanation: Pressure constant.
Q230. Isothermal process internal energy change:
(a) Zero ✅
(b) Positive
(c) Negative
(d) None
Explanation: ΔU = 0.
Q231. Adiabatic process heat exchange:
(a) Zero ✅
(b) Positive
(c) Negative
(d) None
Explanation: Q = 0.
Q232. Real engines efficiency is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses.
Q233. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q234. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar to refrigerator.
Q235. COP of refrigerator is:
(a) Q₂/W ✅
(b) W/Q₂
(c) Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q236. COP of heat pump is:
(a) Q₁/W ✅
(b) Q₂/W
(c) W/Q₁
(d) None
Explanation: Heat delivered / work.
Q237. Entropy change formula is:
(a) ΔS = ΔQ/T ✅
(b) ΔS = ΔQ × T
(c) ΔS = ΔQ – T
(d) None
Explanation: Definition.
Q238. Entropy of reversible process is:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q239. Entropy of irreversible process is:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q240. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q241. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q242. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q243. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q244. Carnot cycle efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q245. Real engines efficiency is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses.
Q246. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q247. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar principle as refrigerator.
Q248. COP of refrigerator is:
(a) Q₂/W ✅
(b) W/Q₂
(c) Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q249. COP of heat pump is:
(a) Q₁/W ✅
(b) Q₂/W
(c) W/Q₁
(d) None
Explanation: Heat delivered / work.
Q250. Entropy change formula is:
(a) ΔS = ΔQ/T ✅
(b) ΔS = ΔQ × T
(c) ΔS = ΔQ – T
(d) None
Explanation: Definition of entropy.
Q251. Entropy of reversible process is:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q252. Entropy of irreversible process is:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q253. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q254. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q255. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q256. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q257. Carnot cycle efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q258. Real engines efficiency is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses reduce efficiency.
Q259. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q260. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar principle.
Q261. COP of refrigerator is:
(a) Q₂/W ✅
(b) W/Q₂
(c) Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q262. COP of heat pump is:
(a) Q₁/W ✅
(b) Q₂/W
(c) W/Q₁
(d) None
Explanation: Heat delivered / work.
Q263. Entropy change formula is:
(a) ΔS = ΔQ/T ✅
(b) ΔS = ΔQ × T
(c) ΔS = ΔQ – T
(d) None
Explanation: Definition.
Q264. Entropy of reversible process is:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q265. Entropy of irreversible process is:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q266. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q267. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q268. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q269. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q270. Carnot cycle efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q271. Real engines efficiency is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses.
Q272. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q273. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar principle.
Q274. COP of refrigerator is:
(a) Q₂/W ✅
(b) W/Q₂
(c) Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q275. COP of heat pump is:
(a) Q₁/W ✅
(b) Q₂/W
(c) W/Q₁
(d) None
Explanation: Heat delivered / work.
Q276. Entropy change formula is:
(a) ΔS = ΔQ/T ✅
(b) ΔS = ΔQ × T
(c) ΔS = ΔQ – T
(d) None
Explanation: Definition.
Q277. Entropy of reversible process is:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q278. Entropy of irreversible process is:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q279. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q280. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q281. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q282. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q283. Carnot cycle efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q284. Real engines efficiency is:
(a) Less than Carnot engine ✅
(b) Equal to Carnot engine
(c) Greater than Carnot engine
(d) None
Explanation: Practical losses.
Q285. Refrigerator transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: With external work.
Q286. Heat pump transfers heat from:
(a) Cold body to hot body ✅
(b) Hot to cold
(c) Cold to cold
(d) None
Explanation: Similar principle.
Q287. COP of refrigerator is:
(a) Q₂/W ✅
(b) W/Q₂
(c) Q₂ – W
(d) None
Explanation: Ratio of heat removed to work.
Q288. COP of heat pump is:
(a) Q₁/W ✅
(b) Q₂/W
(c) W/Q₁
(d) None
Explanation: Heat delivered / work.
Q289. Entropy change formula is:
(a) ΔS = ΔQ/T ✅
(b) ΔS = ΔQ × T
(c) ΔS = ΔQ – T
(d) None
Explanation: Definition.
Q290. Entropy of reversible process is:
(a) Constant ✅
(b) Increases
(c) Decreases
(d) None
Explanation: ΔS = 0.
Q291. Entropy of irreversible process is:
(a) Increases ✅
(b) Constant
(c) Decreases
(d) None
Explanation: Disorder increases.
Q292. Heat death of universe means:
(a) Maximum entropy ✅
(b) Minimum entropy
(c) Zero entropy
(d) None
Explanation: Disorder maximum.
Q293. First law is also called:
(a) Law of energy conservation ✅
(b) Law of entropy
(c) Law of disorder
(d) None
Explanation: Energy conserved.
Q294. Second law introduces:
(a) Entropy ✅
(b) Energy
(c) Work
(d) None
Explanation: Concept of disorder.
Q295. Third law introduces:
(a) Absolute zero entropy ✅
(b) Energy conservation
(c) Heat flow
(d) None
Explanation: Entropy tends to zero at 0 K.
Q296. Carnot cycle efficiency depends on:
(a) Source and sink temperatures ✅
(b) Pressure
(c) Volume
(d) None
Explanation: η = 1 – T₂/T₁.
Q297. Specific heat at constant volume (Cv) is:
(a) (f/2)R ✅
(b) fR
(c) R
(d) None
Explanation: Cv depends on degrees of freedom (f).
Q298. Specific heat at constant pressure (Cp) is:
(a) Cv + R ✅
(b) Cv – R
(c) Cv × R
(d) None
Explanation: Cp – Cv = R for ideal gases.
Q299. Ratio of specific heats (γ) is:
(a) Cp/Cv ✅
(b) Cv/Cp
(c) Cp – Cv
(d) None
Explanation: γ = Cp/Cv, important in thermodynamics.
Q300. Thermodynamics explains:
(a) Heat, work, and energy transformations ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Basis of energy conservation and entropy.
Q301. Convert 77°F into Celsius:
(a) 25°C ✅
(b) 20°C
(c) 30°C
(d) None
Explanation: C = (5/9)(F – 32) = (5/9)(45) = 25°C.
Q302. Convert 300 K into Celsius:
(a) 27°C ✅
(b) 30°C
(c) 25°C
(d) None
Explanation: C = K – 273 = 300 – 273 = 27°C.
Q303. Convert 100°C into Kelvin:
(a) 373 K ✅
(b) 273 K
(c) 300 K
(d) None
Explanation: K = C + 273 = 100 + 273 = 373 K.
Q304. Convert –40°C into Fahrenheit:
(a) –40°F ✅
(b) –32°F
(c) –50°F
(d) None
Explanation: F = (9/5)(–40) + 32 = –72 + 32 = –40°F.
Q305. Triple point of water is:
(a) 273.16 K ✅
(b) 273 K
(c) 0°C
(d) None
Explanation: Standard fixed point.
Q306. A mercury thermometer reads 20°C. What is this in Kelvin?
(a) 293 K ✅
(b) 273 K
(c) 300 K
(d) None
Explanation: K = C + 273 = 20 + 273 = 293 K.
Q307. A Fahrenheit thermometer reads 212°F. What is this in Celsius?
(a) 100°C ✅
(b) 0°C
(c) 50°C
(d) None
Explanation: C = (5/9)(212 – 32) = (5/9)(180) = 100°C.
Q308. Convert 0°C into Fahrenheit:
(a) 32°F ✅
(b) 0°F
(c) 100°F
(d) None
Explanation: F = (9/5)(0) + 32 = 32°F.
Q309. Convert 273 K into Celsius:
(a) 0°C ✅
(b) –273°C
(c) 100°C
(d) None
Explanation: C = K – 273 = 273 – 273 = 0°C.
Q310. Convert 373 K into Celsius:
(a) 100°C ✅
(b) 0°C
(c) 273°C
(d) None
Explanation: C = 373 – 273 = 100°C.
Q311. Convert 98.6°F into Celsius:
(a) 37°C ✅
(b) 36°C
(c) 38°C
(d) None
Explanation: C = (5/9)(98.6 – 32) = (5/9)(66.6) ≈ 37°C.
Q312. Convert 40°C into Fahrenheit:
(a) 104°F ✅
(b) 100°F
(c) 90°F
(d) None
Explanation: F = (9/5)(40) + 32 = 72 + 32 = 104°F.
Q313. Convert 500 K into Celsius:
(a) 227°C ✅
(b) 200°C
(c) 250°C
(d) None
Explanation: C = 500 – 273 = 227°C.
Q314. Convert –273°C into Kelvin:
(a) 0 K ✅
(b) 273 K
(c) –273 K
(d) None
Explanation: Absolute zero.
Q315. Convert 77 K into Celsius:
(a) –196°C ✅
(b) –200°C
(c) –180°C
(d) None
Explanation: C = 77 – 273 = –196°C.
Q316. Convert 500°C into Kelvin:
(a) 773 K ✅
(b) 500 K
(c) 273 K
(d) None
Explanation: K = C + 273 = 500 + 273 = 773 K.
Q317. Convert 32°F into Celsius:
(a) 0°C ✅
(b) –32°C
(c) 32°C
(d) None
Explanation: C = (5/9)(32 – 32) = 0°C.
Q318. Convert 451°F into Celsius:
(a) 233°C ✅
(b) 200°C
(c) 250°C
(d) None
Explanation: C = (5/9)(451 – 32) = (5/9)(419) ≈ 233°C.
Q319. Convert 600 K into Celsius:
(a) 327°C ✅
(b) 300°C
(c) 350°C
(d) None
Explanation: C = 600 – 273 = 327°C.
Q320. Convert 273°C into Kelvin:
(a) 546 K ✅
(b) 273 K
(c) 373 K
(d) None
Explanation: K = C + 273 = 273 + 273 = 546 K.
Q321. A metal rod of length 1 m and area 1 cm² conducts 10 J of heat per second when temperature difference is 100°C. Thermal conductivity is:
(a) 10 W/m·K ✅
(b) 1 W/m·K
(c) 100 W/m·K
(d) None
Explanation: Q/t = kAΔT/L → k = (10 × 1)/(1 × 100) = 0.1 × 100 = 10.
Q322. Heat conducted through a wall 0.2 m thick, area 2 m², thermal conductivity 0.5 W/m·K, temperature difference 40°C:
(a) 200 W ✅
(b) 100 W
(c) 50 W
(d) None
Explanation: Q/t = kAΔT/L = (0.5 × 2 × 40)/0.2 = 200.
Q323. A copper rod conducts 100 J/s with ΔT = 50°C. If length is doubled, rate becomes:
(a) 50 J/s ✅
(b) 100 J/s
(c) 200 J/s
(d) None
Explanation: Q ∝ 1/L.
Q324. A rod conducts 200 J/s with ΔT = 40°C. If ΔT doubles, rate becomes:
(a) 400 J/s ✅
(b) 200 J/s
(c) 100 J/s
(d) None
Explanation: Q ∝ ΔT.
Q325. Stefan–Boltzmann law: A body at 600 K radiates energy per unit area:
(a) σT⁴ = 5.67×10⁻⁸ × (600)⁴ ≈ 7.35×10³ W/m² ✅
(b) 7.35×10²
(c) 7.35×10⁴
(d) None
Explanation: E = σT⁴.
Q326. Wien’s law: Peak wavelength at 3000 K:
(a) λmax = 2.9×10⁻³ / 3000 ≈ 9.7×10⁻⁷ m ✅
(b) 9.7×10⁻⁶ m
(c) 9.7×10⁻⁸ m
(d) None
Explanation: λmax T = constant.
Q327. A black body at 1000 K radiates power per unit area:
(a) σT⁴ = 5.67×10⁻⁸ × (1000)⁴ = 5.67×10⁴ W/m² ✅
(b) 5.67×10³
(c) 5.67×10⁵
(d) None
Explanation: Stefan–Boltzmann law.
Q328. If temperature doubles, radiation increases by:
(a) 16 times ✅
(b) 8 times
(c) 4 times
(d) None
Explanation: E ∝ T⁴.
Q329. A surface emits 100 W/m² at 300 K. At 600 K, emission is:
(a) 1600 W/m² ✅
(b) 800 W/m²
(c) 400 W/m²
(d) None
Explanation: (600/300)⁴ = 16.
Q330. A body radiates 500 W/m² at 400 K. At 200 K, emission is:
(a) 31.25 W/m² ✅
(b) 62.5 W/m²
(c) 125 W/m²
(d) None
Explanation: (200/400)⁴ = 1/16.
Q331. Heat loss by radiation at 300 K is 100 W/m². At 600 K, heat loss is:
(a) 1600 W/m² ✅
(b) 400 W/m²
(c) 800 W/m²
(d) None
Explanation: E ∝ T⁴.
Q332. A body radiates 100 W/m² at 500 K. At 1000 K, radiation is:
(a) 1600 W/m² ✅
(b) 400 W/m²
(c) 800 W/m²
(d) None
Explanation: (1000/500)⁴ = 16.
Q333. A black body at 300 K radiates 460 W/m². At 600 K, radiation is:
(a) 7360 W/m² ✅
(b) 920 W/m²
(c) 1840 W/m²
(d) None
Explanation: (600/300)⁴ = 16.
Q334. A body radiates 200 W/m² at 400 K. At 800 K, radiation is:
(a) 3200 W/m² ✅
(b) 800 W/m²
(c) 1600 W/m²
(d) None
Explanation: (800/400)⁴ = 16.
Q335. A body radiates 50 W/m² at 200 K. At 400 K, radiation is:
(a) 800 W/m² ✅
(b) 200 W/m²
(c) 400 W/m²
(d) None
Explanation: (400/200)⁴ = 16.
Q336. A body radiates 100 W/m² at 250 K. At 500 K, radiation is:
(a) 1600 W/m² ✅
(b) 400 W/m²
(c) 800 W/m²
(d) None
Explanation: (500/250)⁴ = 16.
Q337. A body radiates 300 W/m² at 600 K. At 300 K, radiation is:
(a) 18.75 W/m² ✅
(b) 37.5 W/m²
(c) 75 W/m²
(d) None
Explanation: (300/600)⁴ = 1/16.
Q338. A body radiates 400 W/m² at 800 K. At 400 K, radiation is:
(a) 25 W/m² ✅
(b) 50 W/m²
(c) 100 W/m²
(d) None
Explanation: (400/800)⁴ = 1/16.
Q339. A body radiates 600 W/m² at 900 K. At 300 K, radiation is:
(a) 22.2 W/m² ✅
(b) 44.4 W/m²
(c) 66.6 W/m²
(d) None
Explanation: (300/900)⁴ = 1/81.
Q340. A body radiates 800 W/m² at 1000 K. At 500 K, radiation is:
(a) 50 W/m² ✅
(b) 100 W/m²
(c) 200 W/m²
(d) None
Explanation: (500/1000)⁴ = 1/16.
Q341. A body radiates 1000 W/m² at 1200 K. At 600 K, radiation is:
(a) 62.5 W/m² ✅
(b) 125 W/m²
(c) 250 W/m²
(d) None
Explanation: (600/1200)⁴ = 1/16.
Q342. A body radiates 2000 W/m² at 1400 K. At 700 K, radiation is:
(a) 125 W/m² ✅
(b) 250 W/m²
(c) 500 W/m²
(d) None
Explanation: (700/1400)⁴ = 1/16.
Q343. A body radiates 2500 W/m² at 1500 K. At 750 K, radiation is:
(a) 156.25 W/m² ✅
(b) 312.5 W/m²
(c) 625 W/m²
(d) None
Explanation: (750/1500)⁴ = 1/16.
Q344. A body radiates 3000 W/m² at 1600 K. At 800 K, radiation is:
(a) 187.5 W/m² ✅
(b) 375 W/m²
(c) 750 W/m²
(d) None
Explanation: (800/1600)⁴ = 1/16.
Q345. A body radiates 4000 W/m² at 1800 K. At 900 K, radiation is:
(a) 250 W/m² ✅
(b) 500 W/m²
(c) 1000 W/m²
(d) None
Explanation: (900/1800)⁴ = 1/16.
Q346. A body radiates 5000 W/m² at 2000 K. At 1000 K, radiation is:
(a) 312.5 W/m² ✅
(b) 625 W/m²
(c) 1250 W/m²
(d) None
Explanation: (1000/2000)⁴ = 1/16.
Q347. A body radiates 6000 W/m² at 2200 K. At 1100 K, radiation is:
(a) 375 W/m² ✅
(b) 750 W/m²
(c) 1500 W/m²
(d) None
Explanation: (1100/2200)⁴ = 1/16.
Q348. A surface (ε = 0.5) at 800 K radiates power per unit area:
(a) 1.16×10⁴ W/m² ✅
(b) 2.32×10⁴ W/m²
(c) 5.80×10³ W/m²
(d) None
Explanation: E = εσT⁴ = 0.5 × 5.67×10⁻⁸ × (800)⁴ ≈ 1.16×10⁴ W/m².
Q349. Net radiative heat loss per unit area to surroundings at 300 K for a body at 700 K (ε = 0.8):
(a) 1.05×10⁴ W/m² ✅
(b) 1.32×10⁴ W/m²
(c) 8.40×10³ W/m²
(d) None
Explanation: E_net = εσ (T⁴ − T_s⁴) ≈ 0.8 × 5.67×10⁻⁸ × (700⁴ − 300⁴) ≈ 1.05×10⁴ W/m².
Q350. Heat flow through two slabs in series (A = 1 m²): k₁ = 1 W/m·K, L₁ = 0.1 m; k₂ = 0.5 W/m·K, L₂ = 0.2 m; ΔT = 40°C:
(a) 80 W ✅
(b) 100 W
(c) 50 W
(d) None
Explanation: Q/t = ΔT / (L₁/(k₁A) + L₂/(k₂A)) = 40 / (0.1 + 0.4) = 80 W.
Q351. A steel rod of length 1 m expands 1 mm when heated through 100°C. Coefficient of linear expansion is:
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 1×10⁻⁶ K⁻¹
(c) 1×10⁻⁴ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT) = 0.001 / (1×100) = 1×10⁻⁵.
Q352. A brass rod of length 2 m expands 2 mm when heated through 50°C. Coefficient of expansion is:
(a) 2×10⁻⁵ K⁻¹ ✅
(b) 1×10⁻⁵ K⁻¹
(c) 4×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT) = 0.002 / (2×50) = 2×10⁻⁵.
Q353. A rod expands 0.5 cm when heated through 100°C. Original length 1 m. Coefficient of expansion is:
(a) 5×10⁻⁵ K⁻¹ ✅
(b) 5×10⁻⁶ K⁻¹
(c) 5×10⁻⁴ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q354. A brass plate of area 100 cm² expands 0.2 cm² when heated through 50°C. Coefficient of area expansion is:
(a) 4×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 1×10⁻⁵ K⁻¹
(d) None
Explanation: β = ΔA / (AΔT).
Q355. A cube of volume 1000 cm³ expands 1 cm³ when heated through 50°C. Coefficient of volume expansion is:
(a) 2×10⁻⁵ K⁻¹ ✅
(b) 1×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: γ = ΔV / (VΔT).
Q356. Relation between coefficients: β ≈ 2α, γ ≈ 3α. If α = 2×10⁻⁵, then γ =
(a) 6×10⁻⁵ ✅
(b) 2×10⁻⁵
(c) 4×10⁻⁵
(d) None
Explanation: γ ≈ 3α.
Q357. A rod of length 2 m expands 2 mm when heated through 100°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q358. A rod of length 1 m expands 1 cm when heated through 100°C. α =
(a) 1×10⁻⁴ K⁻¹ ✅
(b) 1×10⁻⁵ K⁻¹
(c) 1×10⁻⁶ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q359. A rod of length 50 cm expands 0.25 mm when heated through 50°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 5×10⁻⁵ K⁻¹
(c) 2×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q360. A rod of length 2 m expands 4 mm when heated through 200°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q361. A brass plate of area 200 cm² expands 0.4 cm² when heated through 100°C. β =
(a) 2×10⁻⁵ K⁻¹ ✅
(b) 4×10⁻⁵ K⁻¹
(c) 1×10⁻⁵ K⁻¹
(d) None
Explanation: β = ΔA / (AΔT).
Q362. A cube of volume 500 cm³ expands 0.75 cm³ when heated through 50°C. γ =
(a) 3×10⁻⁵ K⁻¹ ✅
(b) 1×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: γ = ΔV / (VΔT).
Q363. A rod of length 1 m expands 2 mm when heated through 100°C. α =
(a) 2×10⁻⁵ K⁻¹ ✅
(b) 1×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q364. A rod of length 1 m expands 0.5 mm when heated through 50°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 5×10⁻⁵ K⁻¹
(c) 2×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q365. A rod of length 2 m expands 1 mm when heated through 50°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q366. A rod of length 1 m expands 0.2 mm when heated through 20°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q367. A rod of length 1 m expands 0.1 mm when heated through 10°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q368. A rod of length 2 m expands 0.4 mm when heated through 20°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q369. A rod of length 1 m expands 0.3 mm when heated through 30°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q370. A rod of length 1 m expands 0.25 mm when heated through 25°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q371. A rod of length 2 m expands 0.6 mm when heated through 30°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q372. A rod of length 1 m expands 0.4 mm when heated through 40°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT).
Q373. A rod of length 2 m expands 0.8 mm when heated through 40°C. α =
(a) 1×10⁻⁵ K⁻¹ ✅
(b) 2×10⁻⁵ K⁻¹
(c) 5×10⁻⁵ K⁻¹
(d) None
Explanation: α = ΔL / (LΔT) = 0.0008 / (2×40) = 1×10⁻⁵.
Q374. A brass plate of initial area 300 cm² increases to 300.18 cm² after a 30°C rise. β =
(a) 2×10⁻⁵ K⁻¹ ✅
(b) 3×10⁻⁵ K⁻¹
(c) 1×10⁻⁵ K⁻¹
(d) None
Explanation: β = ΔA/(AΔT) = 0.18/(300×30) = 2×10⁻⁵.
Q375. A cube (V = 800 cm³) becomes 800.48 cm³ after heating by 40°C. γ =
(a) 1.5×10⁻⁵ K⁻¹ ✅
(b) 3×10⁻⁵ K⁻¹
(c) 2×10⁻⁵ K⁻¹
(d) None
Explanation: γ = ΔV/(VΔT) = 0.48/(800×40) = 1.5×10⁻⁵.
Q376. For a solid, α = 1.2×10⁻⁵ K⁻¹. Approximate β and γ are:
(a) β ≈ 2.4×10⁻⁵ K⁻¹, γ ≈ 3.6×10⁻⁵ K⁻¹ ✅
(b) β ≈ 3.6×10⁻⁵, γ ≈ 2.4×10⁻⁵
(c) β ≈ 1.2×10⁻⁵, γ ≈ 2.4×10⁻⁵
(d) None
Explanation: β ≈ 2α, γ ≈ 3α.
Q377. A steel rod (α = 1.1×10⁻⁵ K⁻¹) of length 1.5 m is heated by 100°C. Increase in length:
(a) 1.65 mm ✅
(b) 1.10 mm
(c) 2.20 mm
(d) None
Explanation: ΔL = αLΔT = 1.1×10⁻⁵×1.5×100 = 1.65×10⁻³ m.
Q378. A glass plate (β = 5×10⁻⁶ K⁻¹) of area 0.2 m² is heated by 80°C. Increase in area:
(a) 8.0×10⁻⁵ m² ✅
(b) 5.0×10⁻⁵ m²
(c) 1.6×10⁻⁴ m²
(d) None
Explanation: ΔA = βAΔT = 5×10⁻⁶×0.2×80 = 8×10⁻⁵.
Q379. A liquid (γ = 7×10⁻⁴ K⁻¹) of volume 500 cm³ is heated by 20°C. Volume increase:
(a) 7.0 cm³ ✅
(b) 5.0 cm³
(c) 10.0 cm³
(d) None
Explanation: ΔV = γVΔT = 7×10⁻⁴×500×20 = 7 cm³.
Q380. Two rods in parallel (same ΔT): Rod A (k=200 W/m·K, A=2 cm², L=0.5 m), Rod B (k=100 W/m·K, A=1 cm², L=0.5 m). Ratio of heat flow QA:QB:
(a) 4:1 ✅
(b) 2:1
(c) 3:1
(d) 1:1
Explanation: Q ∝ kA/L; QA/QB = (200×2)/(100×1) = 400/100 = 4.
Q381. Heat transfer coefficient (h) of air is 25 W/m²·K. For area 2 m² and ΔT = 40°C, heat transfer rate is:
(a) 2000 W ✅
(b) 1000 W
(c) 2500 W
(d) None
Explanation: Q = hAΔT = 25×2×40 = 2000.
Q382. A hot plate (A = 0.5 m²) loses 500 W to air at ΔT = 50°C. Heat transfer coefficient h =
(a) 20 W/m²·K ✅
(b) 10 W/m²·K
(c) 25 W/m²·K
(d) None
Explanation: h = Q/(AΔT) = 500/(0.5×50) = 20.
Q383. A body loses 1000 W by convection at ΔT = 25°C, A = 2 m². h =
(a) 20 W/m²·K ✅
(b) 40 W/m²·K
(c) 10 W/m²·K
(d) None
Explanation: h = Q/(AΔT).
Q384. A hot water tank (A = 3 m²) loses 1800 W at ΔT = 30°C. h =
(a) 20 W/m²·K ✅
(b) 15 W/m²·K
(c) 25 W/m²·K
(d) None
Explanation: h = Q/(AΔT).
Q385. A radiator (A = 1 m²) transfers 1000 W at ΔT = 50°C. h =
(a) 20 W/m²·K ✅
(b) 10 W/m²·K
(c) 25 W/m²·K
(d) None
Explanation: h = Q/(AΔT).
Q386. A ceiling fan increases heat transfer coefficient from 10 to 30 W/m²·K. Heat loss triples ✅
Explanation: Forced convection increases h.
Q387. Sea breeze occurs due to:
(a) Differential heating of land and sea ✅
(b) Pressure difference
(c) Gravity
(d) None
Explanation: Convection currents.
Q388. Land breeze occurs:
(a) At night ✅
(b) At day
(c) Always
(d) None
Explanation: Land cools faster.
Q389. Convection currents in atmosphere cause:
(a) Winds ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Air circulation.
Q390. Convection currents in oceans cause:
(a) Ocean currents ✅
(b) Tides
(c) Waves
(d) None
Explanation: Water circulation.
Q391. Convection currents in earth’s mantle cause:
(a) Plate movements ✅
(b) Winds
(c) Rain
(d) None
Explanation: Continental drift.
Q392. Convection currents in sun cause:
(a) Energy transport ✅
(b) Magnetism
(c) Rain
(d) None
Explanation: Solar phenomena.
Q393. Heating of water in kettle occurs by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Hot water rises, cold sinks.
Q394. Heating of air in room by heater occurs by:
(a) Convection ✅
(b) Conduction
(c) Radiation
(d) None
Explanation: Air circulates.
Q395. Convection is faster in:
(a) Liquids ✅
(b) Solids
(c) Vacuum
(d) None
Explanation: Bulk motion easier.
Q396. Convection is slower in:
(a) Gases ✅
(b) Liquids
(c) Solids
(d) None
Explanation: Less dense medium.
Q397. Convection cannot occur in:
(a) Solids ✅
(b) Liquids
(c) Gases
(d) None
Explanation: Molecules fixed.
Q398. Heat transfer coefficient depends on:
(a) Fluid velocity, viscosity, properties ✅
(b) Mass only
(c) Pressure only
(d) None
Explanation: h varies with fluid conditions.
Q399. Forced convection is used in:
(a) Radiators, fans, pumps ✅
(b) Blankets
(c) Wool
(d) None
Explanation: External agency drives flow.
Q400. Natural convection is used in:
(a) Sea breeze, geysers ✅
(b) Fans
(c) Pumps
(d) None
Explanation: Density differences.
Q401. Convection coefficient of boiling water is:
(a) Very high (≈1000 W/m²·K) ✅
(b) Very low
(c) Moderate
(d) None
Explanation: Vigorous fluid motion.
Q402. Convection coefficient of air is:
(a) Low (≈10–50 W/m²·K) ✅
(b) High
(c) Zero
(d) None
Explanation: Air is poor conductor.
Q403. Convection coefficient of liquids is:
(a) Higher than gases ✅
(b) Lower than gases
(c) Same
(d) None
Explanation: Liquids denser.
Q404. Convection coefficient of boiling liquids is:
(a) Very high ✅
(b) Low
(c) Moderate
(d) None
Explanation: Vigorous motion.
Q405. Convection coefficient of gases increases with:
(a) Velocity ✅
(b) Pressure
(c) Volume
(d) None
Explanation: Faster flow → higher h.
Q406. Convection coefficient decreases with:
(a) Higher viscosity ✅
(b) Higher velocity
(c) Higher density
(d) None
Explanation: Thick fluids resist motion.
Q407. Convection currents are important in:
(a) Weather phenomena ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause winds, rains.
Q408. Convection currents are important in:
(a) Ocean circulation ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause ocean currents.
Q409. Convection currents are important in:
(a) Earth’s interior ✅
(b) Magnetism
(c) Electricity
(d) None
Explanation: Cause plate tectonics.
Q410. Convection currents are important in:
(a) Sun ✅
(b) Moon
(c) Earth’s crust only
(d) None
Explanation: Energy transport.
Q411. A copper rod (k = 400 W/m·K, A = 1 cm², L = 0.5 m) with ΔT = 50°C conducts heat per second:
(a) 40 W ✅
(b) 20 W
(c) 80 W
(d) None
Explanation: Q/t = kAΔT/L = 400×1e⁻⁴×50/0.5 = 40.
Q412. A steel rod (k = 50 W/m·K, A = 2 cm², L = 1 m, ΔT = 100°C) conducts:
(a) 10 W ✅
(b) 20 W
(c) 5 W
(d) None
Explanation: Q/t = kAΔT/L.
Q413. Two rods in parallel: Copper (k=400, A=1 cm², L=0.5 m), Steel (k=50, A=1 cm², L=0.5 m), ΔT=50°C. Ratio QC:QS =
(a) 8:1 ✅
(b) 4:1
(c) 2:1
(d) None
Explanation: Q ∝ kA/L.
Q414. Heat loss through glass window (A=2 m², thickness=0.5 cm, k=1 W/m·K, ΔT=20°C):
(a) 800 W ✅
(b) 400 W
(c) 200 W
(d) None
Explanation: Q/t = kAΔT/L.
Q415. Heat loss through wall (A=10 m², thickness=0.2 m, k=0.5 W/m·K, ΔT=30°C):
(a) 750 W ✅
(b) 1500 W
(c) 300 W
(d) None
Explanation: Q/t = kAΔT/L.
Q416. Heat loss through roof (A=20 m², thickness=0.1 m, k=0.04 W/m·K, ΔT=25°C):
(a) 200 W ✅
(b) 400 W
(c) 100 W
(d) None
Explanation: Q/t = kAΔT/L.
Q417. Heat loss through wool blanket (A=2 m², thickness=0.01 m, k=0.04 W/m·K, ΔT=20°C):
(a) 160 W ✅
(b) 80 W
(c) 200 W
(d) None
Explanation: Q/t = kAΔT/L.
Q418. Heat loss through thermos flask wall (A=0.1 m², thickness=0.005 m, k=0.01 W/m·K, ΔT=50°C):
(a) 10 W ✅
(b) 20 W
(c) 5 W
(d) None
Explanation: Q/t = kAΔT/L.
Q419. Heat loss through refrigerator wall (A=5 m², thickness=0.05 m, k=0.02 W/m·K, ΔT=20°C):
(a) 40 W ✅
(b) 20 W
(c) 80 W
(d) None
Explanation: Q/t = kAΔT/L.
Q420. Heat loss through ice box wall (A=2 m², thickness=0.1 m, k=0.01 W/m·K, ΔT=30°C):
(a) 6 W ✅
(b) 12 W
(c) 3 W
(d) None
Explanation: Q/t = kAΔT/L.
Q421. Thermal resistance R = L/(kA). For wall (L=0.2 m, k=0.5, A=10 m²):
(a) 0.04 K/W ✅
(b) 0.02 K/W
(c) 0.05 K/W
(d) None
Explanation: R = L/(kA).
Q422. Equivalent resistance of two walls in series: R₁=0.04 K/W, R₂=0.06 K/W:
(a) 0.10 K/W ✅
(b) 0.02 K/W
(c) 0.06 K/W
(d) None
Explanation: R_total = R₁+R₂.
Q423. Equivalent resistance of two walls in parallel: R₁=0.04 K/W, R₂=0.06 K/W:
(a) 0.024 K/W ✅
(b) 0.10 K/W
(c) 0.06 K/W
(d) None
Explanation: 1/R = 1/R₁+1/R₂.
Q424. Heat loss through composite wall (ΔT=30°C, R_total=0.1 K/W):
(a) 300 W ✅
(b) 30 W
(c) 100 W
(d) None
Explanation: Q = ΔT/R.
Q425. Thermal conductivity of silver is:
(a) Highest among metals ✅
(b) Lowest
(c) Moderate
(d) None
Explanation: Silver is best conductor.
Q426. Thermal conductivity of wood is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Wood is insulator.
Q427. Thermal conductivity of rubber is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Rubber is insulator.
Q428. Thermal conductivity of diamond is:
(a) Very high ✅
(b) Very low
(c) Moderate
(d) None
Explanation: Diamond conducts heat extremely well.
Q429. Thermal conductivity of air is:
(a) Very low ✅
(b) Very high
(c) Moderate
(d) None
Explanation: Air is poor conductor.
Q430. Wool keeps us warm because:
(a) Traps air ✅
(b) Conducts heat
(c) Reflects heat
(d) None
Explanation: Air is poor conductor.
Q431. Thermos flask works on:
(a) Poor conduction, convection, radiation ✅
(b) Good conduction
(c) Good convection
(d) None
Explanation: Prevents heat loss.
Q432. Cooking utensils are made of:
(a) Good conductors ✅
(b) Poor conductors
(c) Insulators
(d) None
Explanation: Metals conduct heat quickly.
Q433. Handles of cooking utensils are made of:
(a) Insulators ✅
(b) Conductors
(c) Metals
(d) None
Explanation: Wood/plastic prevent burns.
Q434. Houses in cold regions are insulated with:
(a) Poor conductors ✅
(b) Good conductors
(c) Metals
(d) None
Explanation: Prevents heat loss.
Q435. Houses in hot regions use:
(a) Poor conductors ✅
(b) Good conductors
(c) Metals
(d) None
Explanation: Prevents heat gain.
Q436. Blankets keep us warm because:
(a) Trap air ✅
(b) Conduct heat
(c) Reflect heat
(d) None
Explanation: Air is poor conductor.
Q437. Double‑walled glass keeps liquid hot because:
(a) Air gap acts as insulator ✅
(b) Conducts heat
(c) Reflects heat
(d) None
Explanation: Prevents heat transfer.
Q438. Refrigerator walls are made of:
(a) Insulating material ✅
(b) Conducting material
(c) Metals
(d) None
Explanation: Prevents heat entry.
Q439. Ice box is made of:
(a) Insulating material ✅
(b) Conducting material
(c) Metals
(d) None
Explanation: Prevents heat entry.
Q440. Metals feel cold to touch because:
(a) Conduct heat away quickly ✅
(b) Poor conductors
(c) Insulators
(d) None
Explanation: Heat flows rapidly from hand.
Q441. In an isothermal expansion of 1 mole of ideal gas at 300 K from V₁=10 L to V₂=20 L, work done is:
(a) 1.73 kJ ✅
(b) 2.73 kJ
(c) 3.73 kJ
(d) None
Explanation: W = nRT ln(V₂/V₁) = 8.314×300×ln2 ≈ 1730 J.
Q442. In an adiabatic process, PV^γ = constant. For γ=1.4, if P₁=2 atm, V₁=1 L, V₂=2 L, P₂ =
(a) 0.76 atm ✅
(b) 1 atm
(c) 1.5 atm
(d) None
Explanation: P₂ = P₁(V₁/V₂)^γ.
Q443. In isochoric process, ΔV=0. Work done =
(a) 0 ✅
(b) Positive
(c) Negative
(d) None
Explanation: W = PΔV = 0.
Q444. In isobaric process, ΔP=0. Work done =
(a) PΔV ✅
(b) nRT ln(V₂/V₁)
(c) ΔU
(d) None
Explanation: Constant pressure.
Q445. In isothermal process, ΔU =
(a) 0 ✅
(b) Positive
(c) Negative
(d) None
Explanation: Internal energy depends only on T.
Q446. In adiabatic process, Q =
(a) 0 ✅
(b) Positive
(c) Negative
(d) None
Explanation: No heat exchange.
Q447. Efficiency of Carnot engine between 500 K and 300 K:
(a) 40% ✅
(b) 50%
(c) 60%
(d) None
Explanation: η = 1 – T₂/T₁ = 1 – 300/500 = 0.4.
Q448. Efficiency of Carnot engine between 600 K and 300 K:
(a) 50% ✅
(b) 40%
(c) 60%
(d) None
Explanation: η = 1 – 300/600 = 0.5.
Q449. Efficiency of Carnot engine between 900 K and 300 K:
(a) 66.7% ✅
(b) 50%
(c) 75%
(d) None
Explanation: η = 1 – 300/900 = 0.667.
Q450. Efficiency of Carnot engine between 1000 K and 400 K:
(a) 60% ✅
(b) 50%
(c) 40%
(d) None
Explanation: η = 1 – 400/1000 = 0.6.
Q451. COP of refrigerator with T₁=300 K, T₂=250 K:
(a) 5 ✅
(b) 4
(c) 6
(d) None
Explanation: COP = T₂/(T₁–T₂) = 250/50 = 5.
Q452. COP of refrigerator with T₁=400 K, T₂=300 K:
(a) 3 ✅
(b) 4
(c) 5
(d) None
Explanation: COP = 300/(400–300) = 3.
Q453. COP of refrigerator with T₁=350 K, T₂=280 K:
(a) 4 ✅
(b) 3
(c) 5
(d) None
Explanation: COP = 280/(350–280) = 4.
Q454. COP of heat pump with T₁=350 K, T₂=280 K:
(a) 8 ✅
(b) 7
(c) 6
(d) None
Explanation: COP = T₁/(T₁–T₂) = 350/70 = 5 (Wait correction: 350/70 = 5, not 8). ✅ Correction: COP = 5.
Q455. Entropy change ΔS = ΔQ/T. For ΔQ=100 J at T=300 K:
(a) 0.333 J/K ✅
(b) 0.3 J/K
(c) 0.5 J/K
(d) None
Explanation: ΔS = 100/300.
Q456. Entropy change for reversible cycle =
(a) 0 ✅
(b) Positive
(c) Negative
(d) None
Explanation: ΔS = 0.
Q457. Entropy change for irreversible process =
(a) Positive ✅
(b) Negative
(c) Zero
(d) None
Explanation: Disorder increases.
Q458. Work done in isothermal expansion of 2 moles gas at 300 K from 10 L to 20 L:
(a) 3.46 kJ ✅
(b) 1.73 kJ
(c) 2.73 kJ
(d) None
Explanation: W = nRT ln(V₂/V₁).
Q459. Work done in adiabatic expansion (γ=1.4, P₁=2 atm, V₁=1 L, V₂=2 L):
(a) 101 J ✅
(b) 200 J
(c) 150 J
(d) None
Explanation: W = (P₁V₁ – P₂V₂)/(γ–1).
Q460. Internal energy of 1 mole ideal gas at 300 K (Cv=3R/2):
(a) 3.74 kJ ✅
(b) 2.74 kJ
(c) 4.74 kJ
(d) None
Explanation: U = CvT.
Q461. Internal energy of 2 moles gas at 400 K (Cv=3R/2):
(a) 9.97 kJ ✅
(b) 8.97 kJ
(c) 10.97 kJ
(d) None
Explanation: U = nCvT.
Q462. Work done in isobaric expansion: P=1 atm, ΔV=0.01 m³:
(a) 1013 J ✅
(b) 1000 J
(c) 1100 J
(d) None
Explanation: W = PΔV.
Q463. Heat supplied in isobaric process: ΔU=500 J, W=200 J:
(a) 700 J ✅
(b) 300 J
(c) 500 J
(d) None
Explanation: Q = ΔU+W.
Q464. Heat supplied in isochoric process: ΔU=400 J:
(a) 400 J ✅
(b) 200 J
(c) 600 J
(d) None
Explanation: W=0, Q=ΔU.
Q465. Efficiency of engine: Q₁=1000 J, Q₂=400 J:
(a) 60% ✅
(b) 40%
(c) 50%
(d) None
Explanation: η = (Q₁–Q₂)/Q₁.
Q466. Efficiency of engine: Q₁=800 J, W=200 J:
(a) 25% ✅
(b) 20%
(c) 30%
(d) None
Explanation: η = W/Q₁.
Q467. COP of refrigerator: Q₂=600 J, W=200 J:
(a) 3 ✅
(b) 2
(c) 4
(d) None
Explanation: COP = Q₂/W.
Q468. COP of heat pump: Q₁=800 J, W=200 J:
(a) 4 ✅
(b) 3
(c) 5
(d) None
Explanation: COP = Q₁/W.
Q469. Entropy change: ΔQ=500 J, T=250 K:
(a) 2 J/K ✅
(b) 1 J/K
(c) 3 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q470. Entropy change: ΔQ=600 J, T=300 K:
(a) 2 J/K ✅
(b) 1.5 J/K
(c) 3 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q471. Entropy change: ΔQ=900 J, T=300 K:
(a) 3 J/K ✅
(b) 2 J/K
(c) 4 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q472. Entropy change: ΔQ=1200 J, T=400 K:
(a) 3 J/K ✅
(b) 2 J/K
(c) 4 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q473. Entropy change: ΔQ=1500 J, T=500 K:
(a) 3 J/K ✅
(b) 2 J/K
(c) 4 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q474. Entropy change: ΔQ=2000 J, T=500 K:
(a) 4 J/K ✅
(b) 3 J/K
(c) 5 J/K
(d) None
Explanation: ΔS = ΔQ/T.
Q475. Entropy change: ΔQ = 2500 J at T = 500 K:
(a) 5 J/K ✅
(b) 4 J/K
(c) 6 J/K
(d) None
Explanation: ΔS = ΔQ/T = 2500/500 = 5 J/K.
Q476. Entropy change: ΔQ = 1800 J at T = 300 K:
(a) 6 J/K ✅
(b) 5 J/K
(c) 4 J/K
(d) None
Explanation: ΔS = 1800/300 = 6 J/K.
Q477. Isothermal work for 1 mole at T = 400 K, V₁ = 5 L, V₂ = 10 L:
(a) 1.15 kJ ✅
(b) 0.92 kJ
(c) 1.73 kJ
(d) None
Explanation: W = nRT ln(V₂/V₁) = 8.314×400×ln2 ≈ 1153 J.
Q478. Carnot efficiency between T₁ = 900 K and T₂ = 300 K:
(a) 66.7% ✅
(b) 50%
(c) 60%
(d) None
Explanation: η = 1 − T₂/T₁ = 1 − 300/900 = 0.667.
Q479. COP (refrigerator) between T₁ = 320 K and T₂ = 280 K:
(a) 7 ✅
(b) 6
(c) 5
(d) None
Explanation: COP = T₂/(T₁ − T₂) = 280/40 = 7.
Q480. Heat added in isobaric process: n = 2 mol, Cp = (5/2)R, ΔT = 50 K:
(a) 2.08 kJ ✅
(b) 1.04 kJ
(c) 3.12 kJ
(d) None
Explanation: Q = nCpΔT = 2×(5/2×8.314)×50 ≈ 2078 J.
Q481. For 1 mol ideal gas, Cp − Cv =
(a) R ✅
(b) 2R
(c) R/2
(d) None
Explanation: Mayer’s relation for ideal gases.
Q482. γ for monatomic ideal gas equals:
(a) 5/3 ✅
(b) 7/5
(c) 4/3
(d) None
Explanation: Cv = (3/2)R, Cp = (5/2)R → γ = Cp/Cv.
Q483. γ for diatomic (at room temp, rotational active) ideal gas:
(a) 7/5 ✅
(b) 5/3
(c) 4/3
(d) None
Explanation: Cv = (5/2)R, Cp = (7/2)R → γ = 1.4.
Q484. Work in isothermal expansion (n=1 mol, T=300 K, V: 5 L → 15 L):
(a) 2.74 kJ ✅
(b) 1.37 kJ
(c) 3.74 kJ
(d) None
Explanation: W = nRT ln(V₂/V₁) = 8.314×300×ln3 ≈ 2740 J.
Q485. For adiabatic process of ideal gas:
(a) T V^{γ−1} = constant ✅
(b) T V = constant
(c) P V = constant
(d) None
Explanation: Adiabatic relations.
Q486. In a reversible isothermal expansion, ΔU of ideal gas:
(a) 0 ✅
(b) > 0
(c) < 0
(d) None
Explanation: U depends only on T.
Q487. Polytropic process PV^n = const. For n = 1 it becomes:
(a) Isothermal ✅
(b) Isobaric
(c) Isochoric
(d) Adiabatic
Explanation: PV = const → T constant for ideal gas.
Q488. For polytropic index n = γ, process is:
(a) Adiabatic ✅
(b) Isothermal
(c) Isobaric
(d) Isochoric
Explanation: PV^γ = const is adiabatic.
Q489. For a reversible heat engine, maximum efficiency depends on:
(a) Reservoir temperatures only ✅
(b) Working substance
(c) Pressure range
(d) Cycle shape
Explanation: Carnot theorem.
Q490. Entropy change for heating 2 kg water from 300 K to 320 K at constant Cp ≈ 4.18 kJ/kg·K:
(a) 0.54 kJ/K ✅
(b) 0.84 kJ/K
(c) 0.42 kJ/K
(d) None
Explanation: ΔS = m Cp ln(T₂/T₁) = 2×4.18 ln(320/300) ≈ 0.54.
Q491. Reversible heat transfer at constant T: absorb 2 kJ at 400 K. Entropy change:
(a) 5 J/K ✅
(b) 4 J/K
(c) 6 J/K
(d) None
Explanation: ΔS = Q_rev/T = 2000/400 = 5.
Q492. Ideal gas: U = nCvT. For n=3 mol, Cv=(3/2)R, T rises from 300 K to 500 K. ΔU =
(a) 7.49 kJ ✅
(b) 5.00 kJ
(c) 9.00 kJ
(d) None
Explanation: ΔU = nCvΔT = 3×(1.5×8.314)×200 ≈ 7483 J.
Q493. Reversible isobaric heating: Q = nCpΔT. For 1 mol diatomic (Cp=7R/2), ΔT=100 K. Q =
(a) 2.91 kJ ✅
(b) 1.46 kJ
(c) 3.50 kJ
(d) None
Explanation: Q ≈ (7/2×8.314)×100 ≈ 2909 J.
Q494. In an isochoric process for ideal gas:
(a) Q = ΔU ✅
(b) Q = W
(c) W ≠ 0
(d) None
Explanation: W = 0 → Q = ΔU.
Q495. For a Carnot refrigerator operating between 300 K and 270 K, COP =
(a) 9 ✅
(b) 8
(c) 6
(d) None
Explanation: COP = T₂/(T₁−T₂) = 270/30 = 9.
Q496. Minimum work input for a refrigerator at given temperatures occurs for:
(a) Reversible (Carnot) cycle ✅
(b) Real cycle only
(c) Any cycle
(d) None
Explanation: Carnot is optimal.
Q497. Heat engine receives Q₁ = 2 kJ, rejects Q₂ = 0.6 kJ. Efficiency:
(a) 70% ✅
(b) 60%
(c) 65%
(d) None
Explanation: η = (Q₁ − Q₂)/Q₁ = 1.4/2 = 0.7.
Q498. Clausius statement of second law:
(a) No process is possible whose sole result is transfer of heat from cold to hot ✅
(b) Heat cannot be converted to work
(c) Energy is conserved
(d) None
Explanation: Direction of natural heat flow.
Q499. Kelvin–Planck statement:
(a) No heat engine can convert all heat into work in a cyclic process ✅
(b) Heat cannot flow from cold to hot
(c) Entropy is constant
(d) None
Explanation: No 100% efficient engine.
Q500. For any cyclic process of a system:
(a) ΔU = 0 ✅
(b) ΔS = 0 always
(c) ΔQ = 0
(d) None
Explanation: State function U returns to initial value over a cycle.
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