MCQs on first law of thermodynamics

MCQs on first law of thermodynamics

Hello Students, how are you all hope you all will be good, in this Page we have shared with you more than 20 Important MCQ on first law of thermodynamics with answers which is helpful for various entrance exams preparation. This first law of  thermodynamics Mcq pdf will help you enhance your performance in entrance exams like NEET and JEE.  mcq on first law of thermodynamics in chemistry is important chapter for Class 11 and class 12 Students.

1st law of thermodynamics mcq


MCQs on first law of thermodynamics

1. Which of the following is not a statement of law of thermodynamics

a) Enegy can neither be created nor be destroy

b) The total energy of the universe 

remains constant

c) Enthalpy change depends only upon initial and final state

d) It is impossible to construct a

perpetual motion machine.

Answer : c



2. Which of the following is correct expression of the first law of thermodynamics?

a) q=   H - W

b)   H=q+W

c)  U= q+ W

d)  U=  H +P  V

Answer : b



3.The first law of thermodynamics fails to decide____________

a) the direction of the the process

b) the extent of conversion of one form of energy to another

c) both these

d) none of these

Answer : c



4.The first law of thermodynanmics is also known as,

a) law of mass action

b) law of conservation of mass

c) law of conservation of energy

d) law of conservation of mass and energy

Answer : c



5. First law of thermodynamics in isochoric process is mathematically expressed as,___________

a ) q=  U- P   V

b)  U=q+ W

c) q= P   V  -  U

d) q=  U

Answer : d


6. A system changes from state A to state B. The change in internal energy is given by   U= UB-  UA This relationship is valid if________

a) the change is brought about in a reversible manner

b) the change is brought about in an irreversible manners 

c) the change is brought about at constant pressure

d) the change is brought about in a manner irrespective of the above.

Answer : d



7.  For an ideal gas undergoing expansion in vaccum, (A) q=0, (B) W=0, (C)    U =0

the correct statements among the above are________

a) A and B only

b) A and C only

c) B and C only

d) all

Answer :d



8. For an infinitesimal small change the first law of thermodynamic can be stated as__________

a) dq= dU + PdV

b) dq= dU- W

c) dq-dU = dP.dV

d dq= U- PdV

Answer :a



9. Which of the following statement is correct?

a) Internal energy is a state function but work is not

b) Work is a state function but internal

energy is not

c) Both internal energy and work are

state functions

d) Neither internal energy nor work is a state function

Answer :a



10. A gas absorbs 250 J of heat and expands froms 1 litre to 10 litre at constant external pressuare of 0.5 atm. The values of 9.W and U will be respectively

a) 250 J, 456 J. 710J

b) -250 J, 456J,  206J

c) -250J, -456J, -206 J

d) 250J, -456J, -206 J

Answer : d


11. According to the latest S.I conventions, which one of the following  is not correct?

a) The heat absorbed by a system is

taken as positive

b) If a system is accompanied by

decrease in energy, AU is negative

c) The work done by the system is taken as positive

d) All the above three statements are correct

Answer : c



12. Which one of the following statements is correct?

a) the total mass and energy of an isolated system, taken together remains constant

b) internal energy of a system includes the potential energy due to the position of the system in space

c) AU depends on the path, the system follows

d) AU is always positive in an cyclic process

Answer : a



13. In a change from state A to state B, which is correct?

a) q depends only on the initial and final state

b) w depends only on the initial and final state

c) AU depends only on the initial and

final state

d) AU depends upon the path adopted by A to change into B

Answer : c



14. In a chemical reaction, system absorbs 500 J of heat and does work. The change in internal energy is 250 J. The work done will be_________

a) +250J

b)+750 J

c)-250 J

d) 750 J

Answer : c



15. The incorrect statement in relation to first law of thermodynamies i.e. U = q+ W is, ....

a) q is positive if heat is absorbed by the system and q is negative if heat is released by the system

b) AU is positive if internal energy of the system increases and AU is negative if internal energy

of the system decreases or energy is given out by the system

c) if work is done on the system W is positive and if work is done by the system W is negative

d) q+ is not a state function

Answer : d


16. Which type of energy of molecules

depend on temperature?

a) Translational

b) bonding

c) Rotational

d) vibrational

Answer :b



17. Thermal enrgy is also called as_______

a) kinetic energy

b) rotational

c) bonding energy

d vibrational energy

Answer :a



18. How internal energy will change due to removal of heat and work from the system?

a) decrease

b) increase 

c) remain same

d) none

Answer :a



19 . The translational energy is not possessed by__________

a) Water

b) Cl2 gas

c) ice

d) Argon gas

Answer : c



20. The form of matter possessing the highest magnitude of internal energy is_______

a) Gaseous

b) Liquid

c) Solid

d) the most stable form at S.T.P.

Answer : a