Find the empirical formula of the compounds with the following percentage composition:

Pb = 62.5%, N = 8.5%, O = 29.0%

Calculate the mass of iron in 10 kg of iron ore which contains 80% of pure ferric oxide.

Find the empirical formula of a compound containing 17.64% hydrogen and 82.35% nitrogen.

On analysis, a substance was found to contain

C = 54.54%, H = 9.09%, O = 36.36%

The vapour density of the substance is 44, calculate;

(a) it's empirical formula, and

(b) it's molecular formula