Question

When entering coefficients to balance equations, recall that just writing the symbol implies "1." Therefore, if a coefficient of "1" is required, choose "blank" for that box.
Balance the following reaction.

C2H5 + O2 → CO2 + H2O

Answer 1

The balanced equation for the combustion reaction is as follows
4C₂H₅ + 13O₂ --> 8CO₂ + 10H₂O
coefficients for the reactants and products are 
C₂H₅ - 4
O₂ - 13
CO₂ - 8
H₂O - 10

Answer 2

The given equation is :

C₂H₆ + O₂ → CO₂ + H₂O

An equation is said to be balanced if the number of atoms of one kind is equal in both the reactants as well as the product side. here we have:

Reactants             Products

C = 2                      C= 1

H = 5                      H = 2

O = 2                      O = 3

The balanced equation would be as follows:

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Reactants             Products

C = 4                      C= 4

H = 12                      H = 12

O = 14                     O = 14