2CH4 + 2NH3 + 3O2 ---> 2HCN + 6H2O
10g CH4 x 1molCH4/16.042gCH4 x 2mol HCN/2molCH4 = 0.6mol HCN
12g NH3 x 1molNH3/17.034gNH3 x 2molHCN/2molNH3 = 0.7mol HCN
Methane is the limiting reactant
Use the moles of Hydrogen Cyanide that you would get when used the limiting reactant, Methane
0.6molHCN x 27.028gHCN/1molHCN = 16.2grams --> 16 grams Methane
the answer is temperature