Question

how many oxygen atoms are present on the reactant side before balancing the equation $ch_4 + o_2
ightarrow co_2 + h_2o$?
a. 2
b. 5
c. 4
d. 3

Explanation:

Step1: Identify reactants

The reactants are $CH_4$ and $O_2$.

Step2: Count oxygen atoms in reactants

$CH_4$ has 0 oxygen atoms, and $O_2$ has 2 oxygen atoms. So in total on the reactant - side, there are 2 oxygen atoms.

Answer:

a. 2