The sample of the same gas, x, y and z, for which the ratio of specific heats γ =3/2 have initially the same volume. The volume of the each sample is doubled by adiabatic process in the case of x, by isobaric process in the case of y and by isothermal process in the case of z. If the initial pressure of the sample of x, y and z are in the ratio 2Ö 2 : 1 : 2 then the ratio of the their final pressures is  

1) 2 : 1 : 1
2) 1 : 1 : 1
3) 1 : 2 : 1
4) 1 : 1 : 2