1. A gas absorbs 350 J of heat and does 300 J of work on its surroundings. The change in its internal energy is:
- 650 J
- 50 J
- 300 J
- 350 J
Show answer and explanation
Answer: (B) 50 J
First law: ΔU = Q − W = 350 − 300 = 50 J.
Heat, work, internal energy and first law of thermodynamics: NEET MCQs with answers
120 questions on this topic of Thermodynamics (NEET 2027 syllabus). Here are 12; tap one to see its answer and explanation.
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2. A gas expands at a constant pressure of 300 kPa from 5 L to 11 L. The work done by the gas is:
- 1.8 J
- 4800 J
- 1800 J
- 3300 J
Show answer and explanation
Answer: (C) 1800 J
W = PΔV = (300 × 10³ Pa) × (6 × 10⁻³ m³) = 1800 J.
Quick tip: kPa × L = J, because 10³ × 10⁻³ = 1.
NCERT Class 11, Chapter 11
3. A gas expands at a constant pressure of 150 kPa from 2 L to 8 L. The work done by the gas is:
- 1200 J
- 1500 J
- 900 J
- 0.9 J
Show answer and explanation
Answer: (C) 900 J
W = PΔV = (150 × 10³ Pa) × (6 × 10⁻³ m³) = 900 J.
Quick tip: kPa × L = J, because 10³ × 10⁻³ = 1.
NCERT Class 11, Chapter 11
4. A gas absorbs 650 J of heat and does 450 J of work on its surroundings. The change in its internal energy is:
- 200 J
- 1100 J
- 650 J
- 450 J
Show answer and explanation
Answer: (A) 200 J
First law: ΔU = Q − W = 650 − 450 = 200 J.
5. A gas expands at a constant pressure of 300 kPa from V to V + 5 L. The work done by the gas is:
- 1500 J
- 1.5 × 10⁶ J
- 1.5 J
- 60 J
Show answer and explanation
Answer: (A) 1500 J
W = PΔV = 300 × 10³ Pa × 5 × 10⁻³ m³ = 1500 J.
6. A gas expands at a constant pressure of 200 kPa from 5 L to 13 L. The work done by the gas is:
- 3600 J
- 1600 J
- 1.6 J
- 2600 J
Show answer and explanation
Answer: (B) 1600 J
W = PΔV = (200 × 10³ Pa) × (8 × 10⁻³ m³) = 1600 J.
Quick tip: kPa × L = J, because 10³ × 10⁻³ = 1.
NCERT Class 11, Chapter 11
7. A gas expands at a constant pressure of 450 kPa from V to V + 3 L. The work done by the gas is:
- 150 J
- 1.35 × 10⁶ J
- 1350 J
- 1.35 J
Show answer and explanation
Answer: (C) 1350 J
W = PΔV = 450 × 10³ Pa × 3 × 10⁻³ m³ = 1350 J.
8. At a constant pressure of 350 kPa, a gas expands from 5 L to 8 L. The work done by it is:
- 4550 J
- 1050 J
- 2800 J
- 1.05 J
Show answer and explanation
Answer: (B) 1050 J
W = PΔV = (350 × 10³ Pa) × (3 × 10⁻³ m³) = 1050 J.
Quick tip: kPa × L = J, because 10³ × 10⁻³ = 1.
NCERT Class 11, Chapter 11
9. A gas absorbs 700 J of heat and does 650 J of work on its surroundings. The change in its internal energy is:
- 700 J
- 1350 J
- 50 J
- 650 J
Show answer and explanation
Answer: (C) 50 J
First law: ΔU = Q − W = 700 − 650 = 50 J.
10. A gas expands at a constant pressure of 200 kPa from 2 L to 12 L. The work done by the gas is:
- 2000 J
- 2 J
- 2800 J
- 2400 J
Show answer and explanation
Answer: (A) 2000 J
W = PΔV = (200 × 10³ Pa) × (10 × 10⁻³ m³) = 2000 J.
Quick tip: kPa × L = J, because 10³ × 10⁻³ = 1.
NCERT Class 11, Chapter 11
11. A gas absorbs 550 J of heat and does 100 J of work on its surroundings. The change in its internal energy is:
- 100 J
- 550 J
- 450 J
- 650 J
Show answer and explanation
Answer: (C) 450 J
First law: ΔU = Q − W = 550 − 100 = 450 J.
12. A gas expands at a constant pressure of 300 kPa from V to V + 10 L. The work done by the gas is:
- 3 J
- 30 J
- 3 × 10⁶ J
- 3000 J
Show answer and explanation
Answer: (D) 3000 J
W = PΔV = 300 × 10³ Pa × 10 × 10⁻³ m³ = 3000 J.
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