Q. A 100 g piece of metal at 150°C is placed in 200 g of water at 25°C. What is the final temperature of the system assuming no heat loss? (2019)
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A.
30°C
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B.
40°C
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C.
50°C
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D.
60°C
Solution
Using the principle of conservation of energy, we can calculate the final temperature to be 50°C.
Correct Answer: C — 50°C
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Q. A 5 kg block of metal is heated from 20°C to 100°C. If the specific heat capacity of the metal is 0.5 J/g°C, how much heat is required? (2023)
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A.
2000 J
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B.
2500 J
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C.
3000 J
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D.
3500 J
Solution
Heat (Q) = m * c * ΔT = 5000 g * 0.5 J/g°C * (100°C - 20°C) = 5000 * 0.5 * 80 = 200000 J = 2000 J.
Correct Answer: C — 3000 J
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Q. If 200 g of water at 80°C is mixed with 300 g of water at 20°C, what will be the final temperature of the mixture? (2019)
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A.
30°C
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B.
40°C
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C.
50°C
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D.
60°C
Solution
Using the formula m1c1T1 + m2c2T2 = (m1 + m2)cT, we find T = (200*80 + 300*20) / (200 + 300) = 40°C.
Correct Answer: B — 40°C
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Q. In an adiabatic process, the temperature of a gas decreases. What happens to its pressure? (2021)
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A.
Increases
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B.
Decreases
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C.
Remains constant
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D.
Depends on volume
Solution
In an adiabatic process, as the temperature decreases, the pressure also decreases due to the ideal gas law.
Correct Answer: B — Decreases
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Q. What is the change in internal energy of a system if 500 J of work is done on it and 200 J of heat is lost? (2023)
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A.
300 J
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B.
500 J
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C.
700 J
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D.
900 J
Solution
Change in internal energy (ΔU) = Q - W = -200 J - 500 J = -300 J.
Correct Answer: A — 300 J
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Q. What is the latent heat of fusion of ice if 80 g of ice at 0°C melts to water at 0°C, absorbing 2400 J of heat? (2022)
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A.
30 J/g
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B.
40 J/g
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C.
50 J/g
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D.
60 J/g
Solution
Latent heat of fusion (L) = Q/m = 2400 J / 80 g = 30 J/g.
Correct Answer: B — 40 J/g
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Q. What is the specific heat capacity of a substance if 500 J of heat is required to raise the temperature of 2 kg of the substance by 10°C? (2021)
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A.
25 J/kg°C
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B.
50 J/kg°C
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C.
75 J/kg°C
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D.
100 J/kg°C
Solution
Specific heat capacity (c) = Q / (m * ΔT) = 500 J / (2 kg * 10°C) = 25 J/kg°C.
Correct Answer: B — 50 J/kg°C
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