Answer is: the mass of the carbon is 14.57 grams.
m(H) = 2.45; mass of hydrogen in sample of acetone.
n(H) = m(H) ÷ M(H).
n(H) = 2.45 g ÷ 1.01 g/mol.
n(H) = 2.425 mol; amount of hydrogen.
From molecular formula of acetone: n(C) : n(H) = 3 : 6 (1 : 2).
n(C) = 2.425 mol ÷ 2.
n(C) = 1.212 mol; amount of carbon in the sample.
m(C) = n(C) · M(C).
m(C) = 1.212 mol · 12.01 g/mol.
m(C) = 14.57 g.