Take some ammonium chloride $\left({\mathrm{NH}}_4\mathrm{Cl}\right)$ in a boiling tube and heat it. Keep a wet litmus paper on the mouth of the boiling tube for some time and observe the colour change. What are the changes that can occur? 

Complete the chemical equation and find out the product.

${\mathrm{NH}}_3+\mathrm{HCl}\to \mathrm{\_\_\_\_\_}$

Write the forward and backward reactions for the following chemical equation.

a) ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\leftrightharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$

b) $2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\leftrightharpoons 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

c) ${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{I}}_2\left(\mathrm{g}\right)\leftrightharpoons 2\mathrm{HI}\left(\mathrm{g}\right)$

What happens to the rates of forward and backward reaction as time progresses in the given graph of reversible process? 

Identify the point at which the rates of both forward and backward reactions become equal in the given graph of a reversible process.