What is the mass of :
(a) 1 mole of nitrogen atoms ?
(b) 4 moles of aluminium atoms ?
(c ) 10 moles of sodium sulphate `(Na_(2)SO_(3))` ?
(Atomic masses : `N = 14 u, Al = 27 u , Na = 23 u , S = 32 u` and `O = 16 u`)

Explanation

(a) Mass of 1 mole of = Atomic mass of nitrogen
nitrogen atoms (N) = expressed in grams
`= 14 g`
(b) Mass of 4 moles of aluminium atoms
(c ) Mass of 1 mople of sodium sulphite = Molecular mass of sodium sulphite `(Na_(2)SO_(3))` in grams
= Mass of 2Na + Mass of S + Mass of 3 'O'
`= 2xx 23 + 32 + 3 xx 16`
`= 46 + 32 + 48`
`= 126 g`
So, Mass of 10 moles of ` = 126 xx 10 g`
sodium sulphite `= 1260 g`