UET Lahore ECAT Chemistry: Gases MCQs

UET Lahore ECAT Chemistry: Gases MCQs — sample questions

1. Question 1

   Q1. At constant temperature, the volume of a gas is inversely proportional to pressure. This is known as:

   • A) Charles' Law
   • B) Boyle's Law
   • C) Avogadro's Law
   • D) Graham's Law

   Answer: Boyle's Law

   Explanation: Boyle's Law states that P1V1 = P2V2 at constant temperature, showing inverse proportionality between volume and pressure.

2. Question 2

   Q2. The rate of diffusion of a gas is inversely proportional to the square root of its:

   • A) Molecular mass
   • B) Density
   • C) Pressure
   • D) Temperature

   Answer: Molecular mass

   Explanation: Graham's Law states that rate of diffusion ∝ 1/√M, where M is molecular mass.

3. Question 3

   Q3. The volume occupied by 1 mole of an ideal gas at STP is:

   • A) 11.2 L
   • B) 22.4 L
   • C) 33.6 L
   • D) 44.8 L

   Answer: 22.4 L

   Explanation: At STP, 1 mole of ideal gas occupies 22.4 L, as per Avogadro's hypothesis.

4. Question 4

   Q4. The ratio of specific heats (Cp/Cv) for a diatomic gas is:

   • A) 1.33
   • B) 1.4
   • C) 1.67
   • D) 1.29

   Answer: 1.4

   Explanation: For diatomic gases, Cp/Cv = 7/5 = 1.4, due to 5 degrees of freedom.

5. Question 5

   Q5. The pressure exerted by a mixture of non-reacting gases is the sum of their partial pressures. This is known as:

   • A) Dalton's Law
   • B) Henry's Law
   • C) Raoult's Law
   • D) Boyle's Law

   Answer: Dalton's Law

   Explanation: Dalton's Law states that P_total = P1 + P2 + ... for non-reacting gases.