Physical Chemistry MCQ with Answers

Physical Chemistry MCQ with Answers

166) The vapour pressure of water at 20^oC is 17.5 torr. What will be the number of moles of water present in 1 L of air at 20^oC and 40% relative humidity?

Answer is:

3.82 x 10⁻⁴ mol

Explanation:

n = PV⁄RT

167) 1 mol each of a monoatmoic, diatomic and triatomic gases are mixed. C_p⁄C_v for the mixture is:

Answer is:

1.428

168) An LPG cylinder contains 15 kg of butane gas at 27^oC and 10 atm pressure. It was leaking and its pressure fell down to 8 atm after 1 day. The gas leaked in 5 days is:

Answer is:

15 kg

Explanation:

P1⁄P2 = w1⁄w2

169) Oxygen gas is collected by downward displacement of water in a jar. The level of water inside the jar is adjusted to the height of water outside the jar. When the adjustment is made, the pressure exerted by oxygen is equal to:

Answer is:

Atmospheric pressure minus aqueous tension at that temperature

Explanation:

P (dry O₂) + P (water vapour) = P (wet O₂)

170) The temperature at which the second virial coefficient of a real gas is zero is called:

Answer is:

Boyle′s temperature

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