A) CH4 + 2O2 —> CO2 + 2H2O
B) assuming STP, you will use the 22.4 L to convert to moles (22.4 L in one mole at STP), then convert between compounds using mole to mole ratio from the balanced equation for B C & D
You have 0.650 L of CH4
0.650 L = 1 mole CH4 = 0.029 moles CH4
 ——————
 22.4 L CH4
Now use mole ratio to convert CH4 to O2
(Ratio of 1 mole CH4 for every 2 moles O2)
0.029 moles CH4 = 2 moles O2 = 0.058 
 ——————
 1 mole CH4
Now change back to liters 
0.058 mole O2 = 22.4 L O2 = 1.3 L O2
 —————
 1 mole O2
C) 
0.029 moles CH4 = 1 mole CO2 = 0.029
 ——————
 1 mole CH4
(0.029 moles CH4 is used again since if we start with 0.650 L of CH4 the mole will be 0.029, just saves calculations :) ) 
0.029 mole CO2 = 22.4 L CO2 
 ——————
 1 mole CO2
= 0.65 L CO2
D) 0.029 mole CH4 = 2 mole H2O = 0.058
 ——————
 1 mole CH4
0.058 mole H2O = 22.4 L H2O = 1.3 L H2O
 ——————
 1 mole H2O