When sample a of methane, ch4, decomposes, it produces 35.0 grams of c and 2.04 grams of h. when sample b of ch4 decomposes, it produces 23.0 grams of c. what mass of h is produced by sample b?

Since both samples are pure CH4 (methane), the proportion of C to H that evolves from the decomposition should be equal. In equation form:
35.0 g C / 2.04 g H = 23.0 g C / x g H
Solving for x gives a value of x = 1.3406 g H
So 1.3406 grams of hydrogen will be produced from sample b.