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Class 11 Thermodynamics worksheet
CBSE Physics. First law, work in processes, heat engines, Carnot engine, refrigerators. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
800 J of heat is given to a gas, and the gas does 600 J of work on its surroundings. The change in its internal energy is:
- −200 J
- 1400 J
- 800 J
- 200 J
Answer
(d) 200 J
ΔU = Q − W
- 2.
A gas expands at a constant pressure of 10 × 10⁵ N/m² from 4 L by 18 L more. The work done by the gas is:
- 18,000,000 J
- 18 J
- 18,000 J
- 180,000 J
Answer
(c) 18,000 J
W = pΔV, with 1 L = 10⁻³ m³
- 3.
A heat engine takes in 4100 J from the hot source and does 600 J of work in each cycle. Its efficiency is:
- 683.33%
- 0.15%
- 85.37%
- 14.63%
Answer
(d) 14.63%
η = W/Q₁
Section B · short answer
- 4.
A system absorbs 1200 J of heat and does 1200 J of work. Find the change in its internal energy.
Answer
0 J
ΔU = Q − W
- 5.
4 mol of an ideal gas expands isothermally at 400 K to 2 times its volume. Find the work done by the gas. (R = 8.31 J/mol K, ln 2 = 0.693) (2 decimal places where needed.)
Answer
9,214.13 J
W = nRT ln(V₂/V₁) = 4 × 8.31 × 400 × 1 × 0.693
Section C · long answer
- 6.
A Carnot engine works between 820 K and 280 K and takes in 15,000 J per cycle. (a) Find its efficiency, the work done and the heat rejected per cycle. (b) To what temperature must the sink be lowered for an efficiency of 60%? (2 decimal places where needed.)
Answer
(a) 65.85%; 9,878.05 J; 5,121.95 J. (b) 328 K
η = 1 − T₂/T₁
Fresh sheets for your child
In the app, every Thermodynamics sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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