A salt has the following % composition — Al = 10.50%, K = 15.1%, S = 24.8% and the remaining oxygen. Calculate the empirical formula of the salt. [Al = 27, K = 39, S = 32, O = 16]

What mass of silver chloride will be obtained by adding an excess of hydrochloric acid to a solution of 0.34 g of silver nitrate. [Cl = 35.5, Ag = 108, N = 14, O = 16, H = 1 ]

From the equation : 3Cu + 8HNO₃ ⟶ 3Cu(NO₃)₂+ 4H₂O + 2NO. Calculate

(i) the mass of copper needed to react with 63 g of nitric acid

(ii) the volume of nitric oxide collected at the same time. [Cu = 64, H = 1, O = 16, N = 14]

Zinc blende [ZnS] is roasted in air. Calculate :

(a) The number of moles of sulphur dioxide liberated by 776 g of ZnS and

(b) The weight of ZnS required to produce 22.4 lits. of SO₂ at s.t.p. [S = 32, Zn = 65, O = 16]