**31.** When a gas is heated from 298K to 323K at a constant pressure of 1 atm its volume is

**A.** Increases from V to 1.8 V

**B.** Increases from V to 1.08 V

**C.** Increases from V to 1.5 V

**D.** Increases from V to 2 V

**Answer :** Option B

**Explanation :**

According to Charles’ law

\(\frac{V_{1}}{T_{1}}=\frac{V_{2}}{T_{2}}\)

\(\frac{V_{1}}{298}=\frac{V_{2}}{323}\)

\(\therefore V_{2}=\frac{323}{298}V_{1}\)

\(=1.08V_{1}\)

**32.** At \(20^{\circ}C\) and 760 torr, the sample of air contains 20% \(O_{2}\) & 80% \(N_{2}\) gaseous mixture, find the density of the air (Molarmass \(O_{2}\) = 32 g/mol , \(N_{2}\) = 28 g/mole R =0.082 \(liter\ mole^{-1}K^{-1}\))

**A.** 1.918 \(gL^{-1}\)

**B.** 2.198 \(gL^{-1}\)

**C.** 1.198 \(gL^{-1}\)

**D.** 1.394 \(gL^{-1}\)

**Answer :** Option C

**33.** The ratio of velocities of diffusion of gas A and B is 1 : 4, if the ratio of their masses in a mixture is 2:3, calculate the ratio of their mole fractions (BIT 1990)

**34.** Under same conditions of temperature and pressure the volumes of 14g \(N_{2}\) and 36g of \(O_{3}\) are related as :

**A.** \(2V_{N_{2}}=3V_{O_{3}}\)

**B.** \(3V_{N_{2}}=2V_{O_{3}}\)

**C.** \(3V_{N_{2}}=4V_{O_{3}}\)

**D.** \(4V_{N_{2}}=3V_{O_{3}}\)

**Answer :** Option B

**35.** Equal masses of Hydrogen and oxygen gases are placed in a closed container, at a pressure of 3.4 atm. The contribution of hydrogen gas to the total pressure is

**36.** The kinetic energy of 4.0 moles of \(N_{2}\) gas at \(127^{\circ}C\) is \(\left ( R=2\ cal\ mole^{-1}K^{-1} \right )\)

**37.** The critical temperature of \(H_{2}O\) is higher than \(CO_{2}\) because (IIT 1997)

**A.** fewer electrons than \(CO_{2}\)

**B.** It contains 2- covalent bonds

**C.** Molecular shape is V- shape

**D.** dipole moment of \(H_{2}O\)

**Answer :** Option D

**39.** A 10 L cylinder of nitrogen at 4.0 atm pressure and \(27^{\circ}C^{-}\) developed a leak. When the leak was repaired 2.36 atm of nitrogen remained in the cylinder at \(27^{\circ}C\). How many grams of nitrogen escaped?

**40.** Calculate percentage of \(NO_{2}\) by weight in \(N_{2}O_{4}\) which has vapour density of 36.