**61.** At constant Volume for a fixed number of a moles of a gas, the pressure of the gas increases with the rise in temperature due to

**A.** Increase in average molecules speed

**B.** Increase rate of collisions amongst

**C.** Increase in molecular attraction

**D.** Increase in mean free path

**Answer :** Option A

**62.** Equal mass of methane and oxygen are mixed in an empty container at \(250^{\circ}C\) the fraction of the total pressure exerted by \(O_{2}\) is

**A.** \(\frac{1}{2}\)

**B.** \(\frac{2}{3}\)

**C.** \(\frac{1}{3}\times \frac{273}{298}\)

**D.** \(\frac{1}{3}\)

**Answer :** Option D

**63.**

Find the true and false statements from the following on the basis of given graph

- Maxwell and Boltz mann had studied the distribution of molecules between different possible speeds
- This graph is known as maxwell’s distribution curve in which kinetic energy and molecular speed of gas is studied.
- The fraction molecues with very high or very low speed is very high
- Inecresing the speed fraction also increasing Which becomes maximum and then deereases.
- The top portion of curve indicates maximum fraction of molewles and the speed of molecules is called most probable speed which is indicated by \(\alpha \)
- On increasing temperature the collison of molecules increases and speed of molecules decreases

**64.** When a real gas behaves as an ideal gas ?

**A.** Inter molecular attraction among molecules are negligible then

**B.** At very low pressure and high temperature then

**C.** When molecular size is very very small and negligible to the volume of container then

**D.** In all the above condition

**Answer :** Option D

**65.** What is the ratio of diffusion rate of \(^{238}\textrm{UF}_{6}\) and \(^{235}\textrm{UF}_{6}\) When these gases are diffused under the same condition of temperature and pressure ?

**66.** Molecular mass of \(SO_{2}\) gas is 4 times than \(CH_{4}\) therefore

**A.** Being \(SO_{2}\) and \(CH_{4}\) both gases, they diffuse with same rate

**B.** \(SO_{2}\) gas will diffuse 4 times factor than that of \(CH_{4}\)

**C.** Diffusion of \(SO_{2}\) gas is half than that of \(CH_{4}\)

**D.** \(CH_{4}\) gas found 4 times faster than \(SO_{2}\)

**Answer :** Option C

**67.** 50 ml \(O_{2}\) gas diffused in 80 sec, What time will be required to diffuse same volume of He gas?

**68.** What is the mass (weight) of \(6.022\times 10^{22}\) oxygen molecules ?

**69.** How many molecules of \(5\ O_{2}\) gas will be present in 5.6 litre volume of STP ?

**A.** \(1.5\times 10^{23}\)

**B.** \(6.002\times 10^{23}\)

**C.** \(7.52\times 10^{23}\)

**D.** \(3.01\times 10^{23}\)

**Answer :** Option A

**70.** Molar mass of \(CaCO_{3}\) = 100 gm/mole, how many molecules are present in 20 gm \(\left (CaCO_{3} \right )\) ?

**A.** \(12.44\times 10^{23}\)

**B.** \(1.2044\times 10^{23}\)

**C.** \(1.2044\times 10^{25}\)

**D.** \(1.2044\times 10^{22}\)

**Answer :** Option B