A2 Daily A Level Physics question
In a lab, identical 0.50 kg samples of water and an unknown liquid X are heated by the same immersion heater for the same time. Both start at 20 C. After heating, the water is at 25 C while liquid X is at 28 C. Assume negligible heat loss and no phase change. Which statement about the specific heat capacity of X compared with water is correct?
Answer
The correct answer is D.
Correct: D — c_X is 5/8 of c_water. With the same energy to the same mass, the temperature rise is inversely proportional to specific heat, so c_X/c_water = ΔT_water/ΔT_X = 5/8. A is wrong because a larger temperature rise means a smaller specific heat for the same energy and mass, not larger. B is wrong because equal energy to equal masses does not make c equal when the temperature rises are different. C is wrong because subtracting the rises is irrelevant; the correct ratio uses ΔT_water/ΔT_X, not 5/3.