N₂ + 3 H₂ → 2 NH₃
(The atomic mass of nitrogen is 14, and that of hydrogen is 1)
1 mole of nitrogen (_______g) +
3 moles of hydrogen ( _________ g) →
2 moles of ammonia ( _________ g)

Calculate the number of moles in
(i) 27g of Al
(ii) 1.51 × 10²³ molecules of NH₄Cl

Give the salient features of “Modern atomic theory”.

How many grams are there in the following?
i) 2 moles of hydrogen molecule, H₂
ii) 3 moles of chlorine molecule, Cl₂
iii) 5 moles of sulphur molecule, S₈
iv) 4 moles of phosphorous molecule, P₄

Calculate the % of oxygen in Al₂(SO₄)₃. (Atomic mass: Al-27, O-16, S -32).