Question

what is the missing coefficient to make a balanced equation? 4na + o₂ → ?na₂o

Explanation:

Step1: Count sodium atoms on left - hand side

There are 4 sodium (Na) atoms on the left - hand side of the equation ($4Na + O_2$).

Step2: Determine coefficient for $Na_2O$

In $Na_2O$, each molecule has 2 sodium atoms. To balance the 4 sodium atoms on the left, we need $\frac{4}{2}=2$ molecules of $Na_2O$. Also, on the left - hand side, there are 2 oxygen atoms in $O_2$, and in 2 molecules of $Na_2O$, there are also 2 oxygen atoms.

Answer:

A. 2