10 question-answer on thermodynamics
1. When an ideal monatomic gas is heated at constant pressure, fraction of heat energy supplied which increases the internal energy of gas is:
(a) 2/5
(b) 3/5
(c) 3/7
(d) ¾
Ans:( b)
2. A sample of gas expands from volume V1 to V2. The amount of work done by the gas is max. when the expansion is:
(a) Isothermal
(b) Adiabatic
(c) Isochoric
(d) Same in all the cases
Ans: (a)
3. Calculate change in internal energy when 5 mole of hydrogen is heated to 20˚C from 10˚C, specific heat of hydrogen at constant pressure is 8 cal/mole ˚C.
(a) 200 cals
(b) 350 cals
(c) 300 cal
(d) 475 cals
Ans: (c)
4. When the door of a refrigerator in a room is kept open, the temperature o the room
(a) Decreases
(b) Increases
(c) Remains constant
(d) Cannot say
Ans: (b)
5. A refrigerator acts as
(a) A heat engine
(b) A heat pump
(c) Air cooler
(d) Electric motor
Ans: (b)
6. Which law of thermodynamics leads us to conclude that it is not possible to convert whole of heat into work continuously?
(a) Third law
(b) Second law
(c) First law
(d) Zeroth law
Ans: (b)
7. A thermo dynamical system returns to its initial state. Which of the following is not possible?
(a) Work done is zero
(b) Work done is positive
(c) Work done is negative
(d) Work done is independent of path followed
AnsLd)
8. When the temperature difference between the source and sink increases, the efficiency of the heat engine:
(a) Decreases
(b) Increases
(c) Is not affected
(d) May increase or decrease
Ans: (b)
9. Which of the following is not a reversible process?
(a) Isothermal expansion of a gas
(b) Adiabatic expansion of a gas
(c) Melting of ice
(d) Conduction of heat
Ans: (d)
10. First law of thermodynamics can be explained on the basis of
(a) Boyle’s law
(b) Maxwell’s law
(c) Charle’s law
(d) Joule’s law.
Ans: (d)
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