Count the number of atoms of each elements on left and right of the arrow in the equation `CaO+H_(2)Orarr Ca(OH)_(2)`.

Explanation

1) A chemical reaction written in the form of equation shows the change of reactants to products by an arrow placed between them.
2) The reactants are written on the left side of the arrow.
3) The products are written on the right side of the arrow.
4) The arrow head point towards the product shows the direction in the reaction, they are indicated with a plus `(+)` sign between them.
6) Example : `underset("(reactants)")("calcium oxide")+"water"rarr underset("(products)")("calcium hydroxide")`