A 0.24 g sample of a compound of oxygen and boron was found by analysis to contain 0.096 g of boron and 0.144 g of oxygen. Calculate the percentage composition of the compound by weight.

Mass of the given sample compound = 0.24g

Mass of boron in the given sample compound = 0.096g

Mass of oxygen in the given sample compound = 0.144g

% composition of compound = % of boron and % of oxygen

Therefore % of boron = (mass of boron)/(mass of the sample compound) x 100

% Boron = $\frac{0.096}{0.24}\times 100$ $= 40\%$

Therefore % of oxygen = (mass of oxygen) / (mass of the sample compound) x 100

% Oxygen = $\frac{0.144}{0.24}\times 100 = 60\%$