Calculate the volume at STP occupied by:
(i) 16 g of oxygen
(ii) 2·5 moles of CO₂
(iii) 1 × 10²¹ molecules of oxygen.

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(i) 16 g of oxygen.
Gram molecular mass of oxygen  = 32 g
Now 32 g oxygen at STP occupies volume = 22.4 litres
 16 g oxygen at STP would occupy volume
                               
(ii) 2.5 moles of CO₂
1 mole of carbondioxide at STP occupies = 22.4 litres

(iii)