Calculate the percentage of nitrogen in aluminium nitride.

[Al = 27, N = 14]

Calculate the percentage of sodium in sodium aluminium fluoride (Na₃AlF₆) correct to the nearest whole number.

[F = 19 ; Na = 23 ; Al = 27]

If the relative molecular mass of ammonium nitrate is 80, calculate the percentage of nitrogen and oxygen in ammonium nitrate.

[N = 14, H = 1, O = 16]

Find the total percentage of magnesium in magnesium nitrate crystals, Mg(NO₃)₂.6H₂O

[Mg = 24; N = 14; O = 16 and H = 1]