Free Gases MCQs with Answers

• A. Raised
• B. Depressed
• C. Compressed
• D. Remains same

Explanation: In a manometer, the liquid column on the side exposed to greater pressure is pushed down, so that column is depressed.

• A. 1.65 g/L
• B. 1.67 g/L
• C. 1.68 g/L
• D. None of the above

Explanation: Using the ideal-gas density relation d = PM/RT, d = (1.05 atm x 39.95 g/mol) / (0.0821 L atm mol^-1 K^-1 x 303 K) = 1.69 g/L, which rounds…

• A. CH4
• B. CO2
• C. C2H4
• D. Xe

Explanation: At 273 K and 76 cm Hg, the gas is at STP, where one mole occupies about 22.4 dm3.

• A. 98.5 atm
• B. 96.7 atm
• C. 95.8 atm
• D. 97.1 atm

Explanation: Using PV = nRT, P = nRT/V = (1 mol)(0.0821 L atm K^-1 mol^-1)(300 K)/(0.250 L) = 98.52 atm, which rounds to 98.5 atm.

• A. 0.0821 atm dm3k-1mol-
• B. 0.0821 atm m3k-1mol-1
• C. 2 cal k-1 mol-1
• D. 8.314 Nm2k-1mol-1

Explanation: The gas constant can be written as R = 0.0821 L atm K^-1 mol^-1, equivalent to 0.0821 dm3 atm K^-1 mol^-1, so option a has the intended…

• A. 22.414 m3
• B. 44.828 dm3
• C. 22.414 dm3
• D. 11.212 cm3

Explanation: Apply PV = nRT: V = nRT/P = (1 mol x 0.082057 L atm mol-1 K-1 x 546.5 K)/(2 atm) = 22.414 L. Since 1 L = 1 dm3, the volume is 22.414 dm3.

• A. Half
• B. Double
• C. Same
• D. None

Explanation: For a fixed amount of ideal gas at constant temperature, density is given by d = PM/RT.

• A. one / seventeen
• B. sixteen / seventeen
• C. one / three
• D. two / three

Explanation: For equal masses, take 32 g of each gas: 32 g CH4 ÷ 16 g mol-1 = 2.0 mol CH4, while 32 g O2 ÷ 32 g mol-1 = 1.0 mol O2.

• A. pressure
• B. volume
• C. moles
• D. density

Explanation: The ideal gas equation uses pressure, volume, temperature, and amount of gas in moles: PV = nRT.

• A. increases by two times
• B. increases by four times
• C. decreases by two times
• D. decrease by four times

Explanation: The average translational kinetic energy of gas molecules is proportional to the square of their speed, KE = 1/2 mv^2.

• A. Straight
• B. Parabolic
• C. Zig-zag
• D. Hyperbolic

Explanation: Kinetic molecular theory assumes that gas particles move continuously in straight lines between collisions.

• A. Bohr's Theory
• B. Dalton's Theory
• C. Kinetic Molecular Theory
• D. None

Explanation: Kinetic molecular theory explains the behaviour of matter by relating its macroscopic properties to the motion and collisions of…

• A. H2 at -73oC
• B. CH4 at 300 K
• C. N2 at 1,027oC
• D. O2 at 0oC

Explanation: For gas molecules at comparable conditions, average speed is proportional to the square root of T/M, where T is in kelvin and M is molar…

• A. Double
• B. Same
• C. Half
• D. Four times

Explanation: The average kinetic energy of gas molecules is directly proportional to absolute temperature.

• A. Diffusion
• B. Effusion
• C. Attraction with air
• D. Low dsensity

Explanation: Fragrance molecules move randomly from the region of high concentration near the source into regions of lower concentration, causing…

• A. Gas
• B. Liquid
• C. Solid
• D. Plasma

Explanation: In the usual elementary classification of matter on Earth, solids are considered the most abundant form because most of Earth's mass is…

• A. Three
• B. Four
• C. Five
• D. Two

Explanation: At the basic chemistry level, matter is commonly classified into four states: solid, liquid, gas and plasma.

• A. H2S
• B. NO
• C. Cl2
• D. N2O

Explanation: Graham's law states that diffusion rate is inversely proportional to the square root of molar mass.

• A. Daltons law
• B. Avogadros law
• C. Grahams law
• D. Charles law

Explanation: Graham's law explains both diffusion and effusion by relating rate to molar mass: rate is proportional to 1 divided by the square root of…

• A. 16 gmol-1
• B. 32 gmol-1
• C. 48 gmol-1
• D. 64 gmol-1Mathematics

Explanation: Using Graham's law, rate of H2 divided by rate of unknown gas equals the square root of molar mass of the unknown divided by 2 g mol-1.