Veriy by calculating that
a) 5 moles of `CO_(2)` and 5 moles of `H_(2)O` do not have the same mass.
b) 240 g of calcium and 240 g magnesium elements have a mole ratio of `3:5`

Explanation

(a) Mass of 5 moles of `CO_(2)`
`"Mass of 1 mole of " CO_(2)=12+2xx1=44 "g mol"^(-1)`
`"Mass of 5 mole of " CO_(2)=(5"mol")xx(44"g mol"^(-1))=220g`
Mass of 5 moles of `H_(2)O`
`"Mass of 1 mole of " H_(2)O=2xx1+16=18 "g mol"^(-1)`
`"Mass of 5 mole of " H_(2)O=(5"mol")xx(18 "g mol"^(-1))=90g`
The two values are not equal.
(b) Mass of (Ca)=240g
`"Molar atomic mass of Calcium (Ca)=40"g mol"^(-1)`
`"No. of moles of calcium (Ca)"=((240g))/((40"g mol"^(-1)))=6"mol"`

Mass of magnesium (Mg)=240g
Molar atomic mass of magnesium (Mg)=`24g mol^(-1)`
`"No. of moles of magnesium (Mg)"=((240g))/((24"g mol"^(-1)))=10"mol"`
Ratio may be given as 6 mol: 10 mole or 3:5