Question

if there are 42g of hydrogen (H) in a sample of pure methane (cH4) how many grams of carbon (C) are present

Answer 1

$n(H) = \frac{42 \;g}{1 \;g/mol} = 42 \; mol$

$n(C) = \frac{1}{4}n(H) = \frac{42 \; mol}{4} = 10.5 \;mol$

$m(C) = 10.5 \; mol \times 12 \;g/mol = 126 \;g$

Answer: 126 g