Areaction involves 0.50grams of hydrogen (h2) gas and 1.20 grams of carbon (c) to form methane (ch4). calculate the mass of methane gas formed?

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.