For ideal gases which of the following statements are correct?
i. At constant temperature, the volume of a fixed mass of gas is proportional to the external pressure.
ii. At constant external pressure and temperature, when 1L of N2 reacts with 2L of O2, 2L of NO2 are formed
iii. At a given temperature and external pressure, equal volumes of any ideal gas contain the same number of molecules
iv. At a given temperature, the molecules in any ideal gas have the same average velocity
v. At a given pressure and temperature, the mean-free path of a gas is independent of the volume of the containing vessel a) (ii) and (iii) b) (i), (iii) and (v) c) (ii) and (iii) d) (ii) and (v) e) (ii), (iii) and (v)