What is a chemical equation? Why it is necessary to balance it?

State the information conveyed by the following equation.

$\mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\uparrow \right)$

What is the limitation of the reaction given below:

$\mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\uparrow \right)$

Write the chemical equation for the following word equation and balance it.

Carbon$+$oxygen$\to$carbon dioxide

Write the chemical equation for the following word equation and balance it.

Nitrogen$+$Oxygen$\to$Nitrogen monoxide

Write the chemical equation for the following word equation and balance it.

Calcium$+$Nitrogen$\to$Calcium nitride

Write the chemical equation for the following word equation and balance it.

Calcium oxide$+$Carbon dioxide$\to$Calcium carbonate

Write the chemical equation for the following word equation and balance it.

Magnesium$+$Sulphuric acid$\to$Magnesium sulphate$+$Hydrogen

Write the chemical equation for the following word equation and balance it.

Sodium reacts with water to form sodium hydroxide and hydrogen.