Question

1. na₂s → na + s

Explanation:

Step1: Balance Na atoms

On the left, we have 2 Na atoms in $\ce{Na_{2}S}$. On the right, we have 1 Na atom. So we need to put a coefficient of 2 in front of $\ce{Na}$ to balance Na.
$\ce{Na_{2}S \to 2Na + S}$

Step2: Check S atoms

On the left, we have 1 S atom in $\ce{Na_{2}S}$. On the right, we have 1 S atom. So S is already balanced.

Answer:

$\ce{Na_{2}S \to 2Na + S}$