The balanced chemical equation for the formation of methane from carbon and hydrogen is,
C + 2H2 --> CH4
This suggests that every 12 grams of C needs 4 grams of H in order to produce 16 grams of methane.
0.05 grams of hydrogen (H2) x (16 grams methane / 4 grams H) = 0.2 grams of methane.
1.20 grams carbon x (16 grams carbon / 12 grams of C) = 1.6 grams methane
We take the lower amount of carbon. Thus, the reaction will produce approximately 0.2 grams methane.