1. The change in internal energy of a system is given by which expression?
A.
Final internal energy minus initial internal energy
B.
Initial internal energy minus final internal energy
C.
Heat supplied divided by work done
D.
Work done multiplied by heat supplied
Correct Answer:
Final internal energy minus initial internal energy
Explanation:
The change in internal energy is calculated as ΔU = U_final − U_initial.
2. If the internal energy of a gas increases from 200 J to 500 J, what is its change in internal energy?
A.
−300 J
B.
200 J
C.
300 J
D.
700 J
Correct Answer:
300 J
Explanation:
ΔU = U_final − U_initial = 500 J − 200 J = 300 J.
3. If the internal energy of a system decreases by 150 J, its change in internal energy is:
A.
150 J
B.
−150 J
C.
0 J
D.
300 J
Correct Answer:
−150 J
Explanation:
A decrease in internal energy is represented by a negative change, so ΔU = −150 J.
4. For an ideal gas, internal energy mainly depends on its:
A.
Temperature
B.
Shape of the container
C.
Colour
D.
Position in the room
Correct Answer:
Temperature
Explanation:
For an ideal gas, a change in temperature produces a change in internal energy.
5. A system receives 80 J of heat and does 30 J of work on its surroundings. Using ΔU = Q − W, what is the change in internal energy?
A.
50 J
B.
110 J
C.
−50 J
D.
30 J
Correct Answer:
50 J
Explanation:
Using the given sign convention, ΔU = Q − W = 80 J − 30 J = 50 J.
6. A gas absorbs 40 J of heat, and 70 J of work is done on the gas. What is its change in internal energy?
A.
−30 J
B.
30 J
C.
110 J
D.
70 J
Correct Answer:
110 J
Explanation:
Work done on the gas adds energy to it, so ΔU = heat absorbed + work done on the gas = 40 J + 70 J = 110 J.
7. If a system returns to its original state, what is the net change in its internal energy?
A.
Positive
B.
Negative
C.
Zero
D.
Equal to the heat supplied
Correct Answer:
Zero
Explanation:
Internal energy is a state function. When the final state is the same as the initial state, ΔU = 0.
8. A system has an initial internal energy of 900 J and a change in internal energy of −250 J. What is its final internal energy?
A.
650 J
B.
1150 J
C.
250 J
D.
−650 J
Correct Answer:
650 J
Explanation:
U_final = U_initial + ΔU = 900 J − 250 J = 650 J.
9. When heat is supplied to a system and no work is done, the change in internal energy is equal to:
A.
The heat supplied
B.
Zero in every case
C.
The negative of the heat supplied
D.
The work done by the system
Correct Answer:
The heat supplied
Explanation:
From the first law, ΔU = Q − W. If W = 0, then ΔU = Q.
10. A system loses 60 J of heat and does no work. What is its change in internal energy?
A.
60 J
B.
−60 J
C.
0 J
D.
120 J
Correct Answer:
−60 J
Explanation:
Since no work is done, the change in internal energy equals the heat transfer. Losing 60 J means ΔU = −60 J.
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