Question

Which of the following reactions is characterised by the yellow colour of the product?
(a)$Zn(s)+{{H}_{2}}S{{O}_{4}}\to ZnS{{O}_{4}}+{{H}_{2}}(g)$
(b)$N{{a}_{2}}C{{O}_{3}}+{{H}_{2}}S{{O}_{4}}\to N{{a}_{2}}S{{O}_{4}}+{{H}_{2}}O+C{{O}_{2}}$
(c)$2P{{b}_{3}}{{O}_{4}}\xrightarrow{\Delta }6PbO\left( s \right)+{{O}_{2}}(g)$
(d)$2KCl{{O}_{3}}\xrightarrow{\Delta }2KCl+3{{O}_{2}}(g)$

Answer 1

the answer to this question includes the fact that the coloured compound is formed by the decomposition process that is employed by the heating process. This point leads you to the correct answer.

Complete answer:
We have studied the decomposition reactions and are also familiar with the reactions that make use of heat for the decomposition.
Let us now see the process that is involved in decomposition that is responsible for the yellow coloured product.
In all the given options, the three products among those four that is zinc sulphate, sodium sulphate and potassium chloride are all white in colour.
- The one product that is lead (II) oxide produced by the decomposition of lead (II,IV) oxide is rather having two colours that is depending on which form it exists.
Usually the reactant that is lead (II,IV) oxide $P{{b}_{3}}{{O}_{4}}$ which is also known as minimum or red lead is bright red or orange in colour and when heated subsequently, it forms lead (II) oxide where the lead (II) oxide formed can be of two forms.
- One of the two forms is the litharge form which exists as red in colour whereas the other form is the massicot form that is yellow in colour.

Therefore, the correct answer to this question is the reaction represented in option (c)$2P{{b}_{3}}{{O}_{4}}\xrightarrow{\Delta }6PbO\left( s \right)+{{O}_{2}}(g)$.

Note: Note that in a chemical reaction, the colour of the reactant does not always be the same that is given as a product. Due to the changes in the composition of the products, the colour of the compound also changes.