Question

What needs to happen for the equation CH4 + O2 → CO2 + H2O to be balanced?

Answer 1

B. This is because the Hydrogen and Oxygen need balanced out.

Current-

C-1            |        C-1
H-4            |         H-2
O-2            |         O-3


Adding a coefficient of 2 before oxygen in the reactants and H2O in the products would balance this equation

CH4 + 2O2 → CO2 + 2H2O
C-1            |        C-1
H-4            |         H-4
O-4            |        O-4