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# Convert into mole.(a) 12g of oxygen gas(b) 20g of water(c) 22g of carbon dioxide

(a) Given mass of oxygen gas = 12g

Molar mass of oxygen gas
= 2 × Mass of Oxygen
= 2 × 16 = 32g

$$Number \ of \ moles \$$

= $$Given \ mass \over molar \ mass \ of \ oxygen \ gas$$ $$=$$ $$12 \over 32$$ $$= 0.375 \ moles$$

(b) Given mass of water = 20g

Molar mass of water
= 2 × Mass of Hydrogen + Mass of Oxygen = 2 × 1 + 16 = 18g

$$Number \ of \ moles \$$

= $$Given \ mass \over molar \ mass \ of \ water$$ $$=$$ $$20 \over 18$$ $$= 1.11 \ moles$$

(c) Given mass of carbon dioxide = 22g

Molar mass of carbon dioxide
= Mass of C + 2 × Mass of Oxygen
= 12 + 2 × 16 = 12 + 32 = 44g

$$Number \ of \ moles$$

= $$Given \ mass \over molar \ mass of \ carbon \ dioxide$$ $$=$$ $$22 \over 44$$ $$= 0.5 \ moles$$