Verify by calculation that:
4 moles of `CO_(2)` and 6 moles of `H_(2)O` do not have same mass in grams.

Explanation

Molar mass of `CO_(2) =12 + 2 xx 16 =44g`
1 mole of `CO_(2)` has mass = 44 g
4 moles of `CO_(2)` have mass `= 44 xx 4 = 176 g`
Molar mass of `H_(2)O =2 xx 1 + 16 = 18 g`
1 mole of `H_(2)O` has mass = 18 g
6 moles of `H_(2)O` have mass `= 6xx 18 = 108 g`.
This shows that these have different masses in grams.