Question

Colour of the solution when $KI$ reacts with $B{r_2}$ is:
A. Pale yellow
B. Reddish brown
C. Black
D. None of the above

Answer 1

Hint: in chemistry, various chemicals react in different ways some react homogeneously and some others react to form other compounds. The change in the colour of the compounds may mark the proceeding of the reaction. In other cases, the progress of the reaction is marked by the evolution of certain gases or the formation of certain compounds.

Complete step by step answer:
During chemical reactions, more than one compound will be reacting together for the formation of products. The progress of the reaction can be marked by various forms. The formation of the product may be related to the formation of certain chemicals. They may also be related to colour change or a certain change of the properties of the solution of the reaction vessel.
The compounds given in the question, upon reaction undergo a displacement reaction where a more active halogen displaces the other metal in the salt. In this case, bromine displaces iodine from its salt.
The representation of the above reaction can be given as
$B{r_2} + 2KI \to 2KBr + {I_2}$
In the above reaction, the colour of the solution will change to a different shade of brown since the solutions of bromine and iodine are both of a different shade of brown. Hence the colour of the solution will change to reddish-brown.

So the correct answer is B.

Note: The reactions of chemistry can be broadly classified into addition reaction, displacement reaction, and elimination reaction.
Besides reaction, the chemical group is added to the compound, in the displacement reaction one or more ions are displaced from the compound while in elimination the ion is removed or eliminated from the given compound.