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

\( Number \ of \ moles \)

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