A certain ideal gas has a molar specific heat at constant volume of 20.8 J mol⁻¹ K⁻¹. What is its molar specific heat at constant pressure (R = 8.31 J mol⁻¹ K⁻¹)?
Correct answer A. 29.1 J mol⁻¹ K⁻¹
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MDCAT ECAT Physics MCQs
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For a monatomic ideal gas Cv = 3R/2. What is the value of γ = Cp/Cv?
Correct answer C. 1.67
In deriving Cp − Cv = R, the work done by one mole of an ideal gas heated through 1 K at constant pressure is shown to equal ____.
Correct answer B. R
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When an ideal gas is heated at constant volume, the heat supplied is used ____.
Correct answer A. entirely to increase its internal energy
A gas expands at a constant pressure of 2.0 × 10⁵ Pa from 1.5 L to 4.0 L. How much work does the gas do?
Correct answer B. 500 J
A gas in a cylinder at a constant pressure of 1.0 × 10⁵ Pa pushes a piston of area 0.020 m² outwards through 0.15 m. What work is done by the gas?
Correct answer D. 300 J
How much work is done by a gas during a process in which its volume remains constant?
Correct answer B. Zero
On a pressure–volume graph, the work done by a gas during an expansion is equal to ____.
Correct answer B. the area under the curve between the initial and final volumes
The first law of thermodynamics is essentially a statement of ____.
Correct answer A. the law of conservation of energy
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A gas absorbs 800 J of heat and does 300 J of work on its surroundings. What is the change in its internal energy?
Correct answer A. +500 J
400 J of work is done on a gas while it gives out 150 J of heat. What is the change in its internal energy?
Correct answer D. +250 J
Two bodies placed in thermal contact are said to be in thermal equilibrium when they ____.
Correct answer A. are at the same temperature
Body A is in thermal equilibrium with body C, and body B is also in thermal equilibrium with C. What can be concluded about A and B?
Correct answer C. A and B are in thermal equilibrium with each other
Heat flows spontaneously between two bodies in contact from the body with ____.
Correct answer C. higher temperature to the one with lower temperature
200 g of water at 80 °C is mixed with 300 g of water at 20 °C. Assuming no heat loss, what is the final temperature?
Correct answer A. 44 °C
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How much heat is needed to raise the temperature of 2.0 kg of water by 15 K (specific heat capacity of water = 4200 J kg⁻¹ K⁻¹)?
Correct answer A. 1.3 × 10⁵ J
What is the SI unit of molar specific heat capacity?
Correct answer C. J mol⁻¹ K⁻¹
The molar specific heat of a substance divided by its specific heat capacity (per unit mass) is equal to its ____.
Correct answer C. molar mass
Helium has a molar specific heat at constant volume of 12.5 J mol⁻¹ K⁻¹ and a molar mass of 4.0 g/mol. What is its specific heat at constant volume per kilogram?
Correct answer A. 3.1 × 10³ J kg⁻¹ K⁻¹
Why is the molar specific heat of a gas at constant pressure greater than that at constant volume?
Correct answer A. At constant pressure part of the heat is used to do work as the gas expands