Question

27. A non-metallic element is converted into a compound X after a series of reactions. A little amount of X when tested with blue litmus turns to red. X on complete reaction with another compound Y gave the product which did not respond to litmus test. Identify the correct sequence of the reactions.

(1) $2{\mathrm{SO}}_2+{\mathrm{O}}_2\to 2{\mathrm{SO}}_3$

(2) ${\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{KOH}\to {\mathrm{K}}_2{\mathrm{SO}}_4+2{\mathrm{H}}_2\mathrm{O}$

$\left(3\right){\mathrm{SO}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2{\mathrm{SO}}_4$

$\left(4\right)\mathrm{S}+{\mathrm{O}}_2\to {\mathrm{SO}}_2$

• A. 1342
• B. 4132
• C. 2314
• D. 4321

Answer 1

The correct option is B

4132

Explanation:

• The nonmetallic pure element is sulfur so the last reaction will get the first sequence.

(4) $$\begin{gathered} \mathrm{S}+{\mathrm{O}}_2\to {\mathrm{SO}}_2 \\ \mathrm{Sulphur}\mathrm{Oxygen}\mathrm{Sulphur}\mathrm{dioxide} \end{gathered}$$

• Now, the nonmetal on reaction gives X(SO₂) which turns blue litmus red. Also X is reacted further to give a product, according to the given condition the sequence will have the first reaction.

(1) $$\begin{gathered} 2{\mathrm{SO}}_2+{\mathrm{O}}_2\to 2{\mathrm{SO}}_3 \\ \mathrm{Sulphur}\mathrm{Oxygen}\mathrm{Sulphur} \\ \mathrm{dioxide}\mathrm{trioxide} \end{gathered}$$

• Further reaction of the product gives a compound Y which does not respond to litmus paper which means the compound formed is an acid. So, the third reaction will follow the next sequence.

(3) $$\begin{gathered} {\mathrm{SO}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2{\mathrm{SO}}_4 \\ \mathrm{Sulphur}\mathrm{Water}\mathrm{Sulphuric} \\ \mathrm{trioxide}\mathrm{acid} \end{gathered}$$

• Further reaction of sulphuric acid with a base undergoes neutralization reaction forming a salt along with the water. The salt formed will have no effect on litmus. Therefore, the second reaction will be the last reaction of the sequence.

(2) $$\begin{gathered} {\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{KOH}\to {\mathrm{K}}_2{\mathrm{SO}}_4+2{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Sulphuric}\mathrm{Potassium}\mathrm{Postassium}\mathrm{Water} \\ \mathrm{acid}\mathrm{hydroxide}\mathrm{sulphate}\left(\mathrm{salt}\right) \end{gathered}$$

Hence, option (B) i.e., sequence 4132 is the correct answer.