what is the percentage of sulfur and copper(I) sulfide, Cu2S is the answer 35.58% if not could you show me the formula

1 answer

Cu2S has a molar mass of 159.158 but you need to confirm that by adding the atomic masses of the elements.
Cu = 63.546
S = 32.066, again confirm these.

% Cu = [2xCu/Cu2S]*100 = 79.85% but check my arithmetic.
% S = [32.066/159.158]*100 = 20.15%