Influence of pressure, temperature, concentration and addition of inert gas on a reversible chemical reaction in equilibrium can be explained by formulating the expression for equilibrium constant `K_(c)` or `K_(p)` for the equilibrium. On the other hand Le Chatelier principle can be theoretically used to explain the effect of `P`, `T` or concentration on the physical or chemical equilibrium both.
For the reaction:
`underset(Yellow)(Fe_((aq.))^(3+))+SCN_((aq.))^(-)hArrunderset(Red)([Fe(NCS)]_((aq.))^(2+))`
in equilibrium if little more aqueous solution in `FeCl_(3)` is added, then:

Options

A. forward reaction becomes more and red colour is deepened
B. backward reaction becomes more and red colour faintens
C. solution becomes colourless
D. none of these

Explanation

Addition of `Fe^(2+)` will favour forward reaction.