Use of the Data Booklet is relevant to this question.


The approximate percentage composition of the atmosphere on four different planets is given in

the table below.


The density of a gas may be defined as the mass of 1 dm3

of the gas measured at s.t.p.


Which mixture of gases has the greatest density?


planet major gases /

% by number of molecules

A Jupiter H2 89.8, He 10.2

B Neptune H2

80.0, He 19.0, CH4 1.0

C Saturn H2 96.3, He 3.25, CH4 0.45

D Uranus H2 82.5, He 15.2, CH4 2.3