(i) What is the mass of 1 mole of nitrogen atom?
(ii) How many moles of `SO_(2)` have same mass as 3 moles of oxygen?
(iii) How many molecules are present in 1 ml of water?

Explanation

(i) 1 `times` gram atomic mass of nitrogen atom
`" "1 times 14=14g`
(ii) Mass of 3 moles of oxygen `=3 times 16=48g`
`" "`, Now, mass of `SO_(2)=32+[2 times 16]`
`" "=32+32=64g`
`" "therefore" 64 g of "SO_(2)=` 1 mole
`" 48 g " SO_(2)=(1/64) times 48=0.75` mole
(iii) We know that density of water is 1 g/ml
Hence, 1 g of water = 1 ml of water
Now, We have molecular mass of water
`" "H_(2)O=(1 times 2)+16=18g`
18 g of water contains `6.022 times 10^(23)` molecules
1 g of water will contains `=(6.023 times 10^(23))/18=0.33 times 10^(23)` molecules
So the number of molecules of water in 1 ml `=3.3 times 10^(22)`