When the following equation is balanced with the lowest whole number coefficients possible, what is the coefficient in front of na?

na (s) + h2o (g) yields naoh (aq) + h2 (g)

1
2
3
4

The unbalanced chemical reaction is
Na (s) + H2O (g) yields NaOH (aq) + H2 (g)

By inspection,
There is 1 mole of Na in both sides
There is 2 moles of H in the left and 3 moles in the right side.
There is 1 mole of O in both sides

We balance the reaction by:

2Na (s) + 2H2O (g) yields 2NaOH (aq) + H2 (g)

The answer is 2

The name for subatomic particles in an atom is called a proton