If you have 9 x 1022 particles of dicarbon tetrahydride, how many grams do you have?

Answer 1

dicarbon tetrahydride = C₂H₄ = ethene

molar mass = 2x12 + 4x1 = 24 + 4 = 28 g/mol

9x10²² particles x 1 mol / 6.02x10²³ particles = 1.5x10^-1 mols = 0.15 mols

0.15 mols x 28 g/mol = 4.2 g = 4 g (1 sig. fig.)