Question

1. ca + o₂ → cao

Explanation:

Step1: Balance O atoms

On the left, $O_2$ has 2 O atoms. On the right, $CaO$ has 1 O atom. So we put a coefficient of 2 in front of $CaO$:
$Ca + O_2
ightarrow 2CaO$

Step2: Balance Ca atoms

Now, the right has 2 Ca atoms (from $2CaO$). So we put a coefficient of 2 in front of $Ca$:
$2Ca + O_2
ightarrow 2CaO$

Answer:

$2Ca + O_2 = 2CaO$ (Note: Using $=$ for the balanced equation, replacing $
ightarrow$ for clarity)