Class 11 – Thermodynamics (40 MCQs)
Basic Concepts (1–5)
- In thermodynamics, the “system” refers to:
a) The surroundings
b) The part of the universe under study
c) Heat absorbed only
d) Work done only - Which of the following is a closed system?
a) Boiling water in an open pan
b) Steam in a sealed piston
c) Ice melting in an open container
d) Gas escaping freely - The surroundings are:
a) The part under study
b) Everything outside the system
c) Only the heat bath
d) Only the walls of the container - Isolated systems:
a) Exchange matter only
b) Exchange energy only
c) Exchange neither matter nor energy
d) Exchange both matter and energy - Extensive properties depend on:
a) Amount of substance
b) Nature of substance only
c) Temperature only
d) None of the above
Work, Heat, Energy (6–11)
- Internal energy (U) is:
a) Path function
b) State function
c) Work function
d) Heat function - Work done by a gas during expansion at constant pressure is:
a) PΔV
b) ΔU
c) ΔH
d) Q - Heat absorbed by the system at constant volume changes:
a) Internal energy
b) Enthalpy
c) Pressure
d) Volume - 1 calorie is equal to:
a) 4.18 J
b) 3.14 J
c) 1 J
d) 0.5 J - Work done is positive when:
a) System does work on surroundings
b) Surroundings do work on system
c) Heat is absorbed
d) Temperature rises - Heat is negative when:
a) System absorbs heat
b) System releases heat
c) Work is done on system
d) Volume increases
First Law of Thermodynamics (12–18)
- The first law of thermodynamics states:
a) ΔU = Q + W
b) ΔU = Q – W
c) ΔU = W – Q
d) ΔU = PΔV - For a cyclic process:
a) ΔU = 0
b) ΔH = 0
c) Q = 0
d) W = 0 - For an adiabatic process:
a) Q = 0
b) W = 0
c) ΔU = 0
d) ΔH = 0 - For an isothermal process of ideal gas:
a) ΔU = 0
b) ΔU > 0
c) ΔU < 0
d) ΔH > 0 - If 500 J of heat is added to a system and it does 200 J work, the change in internal energy is:
a) 700 J
b) 300 J
c) –300 J
d) –700 J - In expansion against constant pressure, ΔH is:
a) Equal to ΔU
b) Equal to Q
c) Zero
d) Negative - Which of the following is a state function?
a) Work
b) Heat
c) Internal energy
d) Path
Enthalpy & Hess’s Law (19–25)
- Enthalpy (H) is defined as:
a) H = U – PV
b) H = U + PV
c) H = PV – U
d) H = Q – W - Exothermic reaction:
a) ΔH > 0
b) ΔH < 0
c) ΔU > 0
d) ΔU = 0 - Endothermic reaction:
a) ΔH > 0
b) ΔH < 0
c) ΔU < 0
d) ΔU = 0 - Hess’s Law states:
a) Heat depends on path
b) Total enthalpy change is independent of path
c) ΔU = 0 for cyclic process
d) Work done = 0 in adiabatic process - Standard enthalpy of formation of an element in its natural state is:
a) Zero
b) 1 kJ/mol
c) Negative
d) Positive - Standard enthalpy of combustion refers to:
a) Formation of 1 mole compound
b) Combustion of 1 mole substance in O₂
c) Any chemical reaction
d) None - Enthalpy change in neutralization of an acid by base:
a) Positive
b) Negative
c) Zero
d) Random
State & Path Functions (26–29)
- Internal energy and enthalpy are:
a) Path functions
b) State functions
c) Work functions
d) Heat functions - Work and heat are:
a) State functions
b) Path functions
c) Both
d) None - Expansion work depends on:
a) Path
b) State
c) Internal energy only
d) Enthalpy only - ΔU depends on:
a) Initial and final states only
b) Path only
c) Both path and state
d) None
Standard Enthalpies & Miscellaneous (30–40)
- Standard enthalpy of formation of H₂O(l) is:
a) –285.8 kJ/mol
b) 285.8 kJ/mol
c) 0 kJ/mol
d) 100 kJ/mol - Standard enthalpy of formation of O₂(g) is:
a) 0 kJ/mol
b) 100 kJ/mol
c) –100 kJ/mol
d) 50 kJ/mol - Heat of combustion is always:
a) Positive
b) Negative
c) Zero
d) Depends on substance - In adiabatic expansion, temperature of gas:
a) Increases
b) Decreases
c) Remains same
d) Random - Internal energy of ideal gas depends on:
a) Pressure and volume
b) Temperature only
c) Volume only
d) Pressure only - Work done by gas = 0 in:
a) Isochoric process
b) Isothermal process
c) Adiabatic process
d) All of the above - Heat absorbed by system in isobaric process =
a) ΔU
b) ΔH
c) Zero
d) W - Reaction is spontaneous if ΔG is:
a) Positive
b) Negative
c) Zero
d) Infinity - ΔH of reaction = ΔU + PΔV is:
a) First law equation
b) Definition of enthalpy
c) Hess’s law
d) None - Enthalpy change of melting ice:
a) Positive
b) Negative
c) Zero
d) Random - Work done on system is positive when:
a) System expands
b) Surroundings compress system
c) Heat absorbed
d) No change
Answer Key – Class 11 Chemistry: Thermodynamics (40 MCQs)
Basic Concepts (1–5)
- b) The part of the universe under study – Definition of a system.
- b) Steam in a sealed piston – Closed system exchanges energy but not matter.
- b) Everything outside the system – Surroundings = rest of universe.
- c) Exchange neither matter nor energy – Isolated system.
- a) Amount of substance – Extensive property depends on quantity.
Work, Heat, Energy (6–11)
- b) State function – Internal energy depends only on state.
- a) PΔV – Work done at constant pressure.
- a) Internal energy – Q at constant volume → ΔU.
- a) 4.18 J – 1 cal = 4.18 J.
- a) System does work on surroundings – Positive work done by system.
- b) System releases heat – Heat leaving system is negative.
First Law of Thermodynamics (12–18)
- b) ΔU = Q – W – Work done by system is subtracted.
- a) ΔU = 0 – Cyclic process returns to initial state.
- a) Q = 0 – Adiabatic: no heat exchange.
- a) ΔU = 0 – Isothermal process: temperature constant → ΔU = 0.
- b) 300 J – ΔU = Q – W = 500 – 200 = 300 J.
- b) Equal to Q – At constant pressure, ΔH = heat absorbed.
- c) Internal energy – ΔU is a state function.
Enthalpy & Hess’s Law (19–25)
- b) H = U + PV – Definition of enthalpy.
- b) ΔH < 0 – Exothermic reaction releases heat.
- a) ΔH > 0 – Endothermic absorbs heat.
- b) Total enthalpy change is independent of path – Hess’s law.
- a) Zero – Element in natural state, ΔHf° = 0.
- b) Combustion of 1 mole substance in O₂ – Definition of standard enthalpy of combustion.
- b) Negative – Neutralization of strong acid + strong base releases heat.
State & Path Functions (26–29)
- b) State functions – U and H depend on state only.
- b) Path functions – Work and heat depend on path.
- a) Path – Expansion work depends on how expansion occurs.
- a) Initial and final states only – ΔU is state function.
Standard Enthalpies & Miscellaneous (30–40)
- a) –285.8 kJ/mol – Standard ΔHf of H₂O(l).
- a) 0 kJ/mol – Standard ΔHf of elements in natural state = 0.
- b) Negative – Combustion is exothermic.
- b) Decreases – Adiabatic expansion cools gas.
- b) Temperature only – Internal energy of ideal gas depends on temperature.
- a) Isochoric process – No volume change → W = 0.
- b) ΔH – Heat at constant pressure = enthalpy change.
- b) Negative – Spontaneous reaction: ΔG < 0.
- b) Definition of enthalpy – ΔH = ΔU + PΔV.
- a) Positive – Melting ice absorbs heat.
- b) Surroundings compress system – Work done on system is positive.
Disclaimer:
All MCQs on this page are created for educational purposes only. They are intended for practice and NEET/Class 11 Chemistry preparation and do not guarantee any specific exam results.