720cc of methane diffused through a porous membrane in 30min. Under identical conditions 240cc of gas 'X'diffused in 20 min. Calculate the molecular weight of 'X'.

Explanation

Rate of diffusion of methane `= 720//30 = 24 cc m^(-1)`
Rate of diffusion of gas .X.= `240//20 = 12 cc m^(-1)`
Ratio of rates of diffusion is given as
` (r_1)/(r_2) = sqrt((M_2)/(M_1)) implies (24)/(12) = sqrt((M_2)/(M_1)) implies 2 =sqrt((M_2)/(16))`
Molecular weight of .X. `= 2^2 xx 16 = 64`