Convert into moles :
(a) 12 g of oxygen gas
(b) 20 g of water
(c ) 22 g of carbon dioxide
(Atomic masses : `O = 16 u, H = 1 u` and `C = 12 u`)

Explanation

(a) Molar mass of `O_(2) = 2 xx 16 = 32 g`
Number of moles in 12 g of `O_(2)`
`=("Given mass")/("Molar mass") = 12/32 = 0.375` mole
(b) Molar mass of `H_(2)O = 2 xx 1 + 16 = 18 g`
`therefore` Number of moles in 20 g of `H_(2)O = 20/18 = 1.11` moles
(c) Molar mass of `CO_(2) = 12 + 16 xx 2 = 12 + 32 = 44 g`
`therefore` Number of moles in 22 g of `CO_(2) = 22/44 = 0.5` mole