The decreasing order of the mass of the molecules are:
Fe2O3>C6H14>CaCO>NO2
Explanation:
Let us calculate the atomic mass of the molecules given:
C6H14 Atomic mass of 1 carbon atom =12.01 amu
so, 6*12+1*14 Atomic mass of hydrogen=1.007
= 86 g/mol
Atomic mass of NO2
= 14+ (2*15.9)
= 14+ 31.8
= 45.8 g/mol
Atomic mass of Fe203
( 2*55.845)+ (3*15.9)
= 159.69 g/mol
Atomic mass of CaCO
40.07+12.0107+15.99
= 68.07g/mol
The decreasing order of the mass of the molecules are:
Fe2O3>C6H14>CaCO>NO2
