To an evacuated vessel with movable piston under external pressure of 1 atm, 0.1 mol of He and 1.0 mol of an unknown compound (vapour pressure 0.68 atm, at 0^oC) are introduced. Considering the ideal gas behaviour, the total volume (in litre) of the gases at 0^oC is close to

At 27^oC, hydrogen is leaked through a tiny hole into a vessel for 20 minutes. Another unknown gas at the same temperature and pressure as that of H₂ is leaked through the same hole for 20 minutes After the effusion of the gases the mixture exerts a pressure of 6 atmosphere. The hydrogen content of the mixture is 0.7 mole. If the volume of ther container is 3 litres, what is the molecular weight of the unknown gas?

A spherical balloon of 21 cm diameter is to be filled up with hydrogen at N.T.P from a cylinder containing the gas at 20 atmospheres at 27^oC. If the cylinder can hold 2.82 litres of water, calculate the number of balloons that can be filled up.