Gas Law

1. At 100°C and 1 atm, if the density of liquid water is 1.0 g cm-3 and that of water vapour is 0.0006 g cm-3, then the volume occupied by water molecules in one litre of steam at that temperature is: (a) 6cm3 (b) 60cm3 (c) 0.6cm3 (d) 0.06cm3 2. If air contains N2 and O2 in volume ratio 4 : 1. The average vapour density of air is: (a) 14.5 (b) 16.5 (c) 14.4 (d) 29.0 3. If pressure of a gas contained in a closed vessel is increased by 0.4% when heated by 1°C its initial temperature must be: (a) 250 K (b) 250°C (c) 2500 K (d) 25°C 4. At NTP, 5.6 litre of a gas weighs 8 g. The vapour density of the gas is: (a) 32 (b) 40 (c) 16 (d) 8 5. A closed vessel contains equal number of oxygen and hydrogen molecules at a total pressure of 740 mm. If oxygen is removed from the system, the pressure: (a) Becomes half of 740 mm (b) Remains unchanged (c) Becomes 1/9th of 740 mm (d) Becomes double of 740 mm 6. Four one litre flasks are separately filled with the gases, O2,F2,CH4 and CO2 under the same conditions. The ratio of number of molecules in these gases: (a) 2 : 2 : 4 : 3 (b) 1 : 1 : 1 : 1 (c) 1 : 2 : 3 : 4 (d) 2 : 2: 3 : 4 7. 120 g of an ideal gas of molecular weight 40 mol-1 are confined to a volume of 20 litre at 400K. Using R =0.0821 litre atm K-1 mol-1, the pressure of the gas is: (a) 4.90 atm (b) 4.92 atm (c) 5.02 atm (d) 4.96 atm 8. A gas is found to have formula [CO]X. Its VD is 70. The value of x must be: (a) 3 (b) 5 (c) 6 (d) 2.5 9. 4.0 g of argon has pressure P and temperature T K in a vessel. On keeping the vessel at 50° higher temperature, 0.8 g of argon was given out to maintain the pressure P. The original temperature was: (a) 73 K (b) 100 K (c) 200 K (d) 510K 10. For a given mass of a gas, if pressure is reduced to half and temperature is increased two times, then the volume would become: (a) V/4 (b) 2V2 (c) 6K (d) 4V 11. A mixture of helium and argon contains 3 mole of He for every 2 mole of Ar. The partial pressure of argon is: (a) 2/3 the total pressure (b) 1/3 the total pressure (c) 2/5 the total pressure (d) 1/5 the total pressure 12. A gaseous mixture contains oxygen and nitrogen in the ratio of 1 : 4 by weight. Therefore, the ratio of their number of molecules is: (a) 1 : 4 (b) 1 : 8 (c) 7 : 32 (d) 3 : 16 13. O2 is collected over water at 20°C. The pressure inside shown by the gas is 740 mm of Hg. What is the pressure due to O2 alone if vapour pressure of H2O is 18 mm at 20°C? (a) 722 mm (b) 740 mm (c) 758 mm (d) None of these 14. Under identical conditions of temperature the density of a gas A is three times that of gas B while molecular mass of gas B is twice that of A. The ratio of pressures of A and B will be: (a) 6 (b) 1/6 (c) 2/3 (d) 3/2 15. Volume occupied by molecules of one mole gas at NTP, each having radius of 108 cm is: (a) 22.0 litre (b) 22.4 litre (c) 10.09 mL (d) 10.09 litre

Answers:1. (c) 2.(c) 3. (a) 4. (c) 5. (a) 6. (b) 7. (b)8. (b)9. (c) 10. (d) 11. (c) 12.(c)

13.(a) 14. (a) 15. (c)