Question

Assertion: In the fountain experiment the gas used is hydrogen chloride or ammonia.
Reason: Ammonia has a very pungent irritating smell which is highly distinct and can be distinguished from the choking smell of hydrochloric acid.
(a) Both assertion and reason are correct and reason is the correct explanation for assertion.
(b) Both assertion and reason are correct but reason is not the correct explanation for assertion.
(c) Assertion is correct but reason is incorrect
(d) Both assertion and reason are incorrect

Answer 1

Hint: We should know the properties of two compounds like their physical state, their appearance and smell which is one of the important criteria with which we could easily observe and state the difference between the two elements before doing any detection test.

Complete answer:
So in the question, two statements, an assertion statement, and the reason associated with the assertion is given. We have to comment on whether the reason given is correct according to the assertion statement.
So first let us analyze the two statements. In the assertion statement, it is given as in the fountain experiment the gas used is hydrogen chloride or ammonia, which is correct. We use both gas either HCl or ammonia for the fountain experiment. So the reason statement given is correct.
Now we have to discuss the reason statement given. The reason is given as ammonia gas possess a very pungent irritating smell and which is highly distinct and we can distinguish between the smell of ammonia from the choking smell of hydrochloric acid.
But the reason statement is not true because we detect the gas present inside the flask with ammonium hydroxide solution. We use a glass rod that is dipped in ammonium hydroxide solution and introduces the glass rod near the flask if it forms white dense fumes, then the gas present in the flask is HCl. The HCl reacts with ammonium hydroxide and gives ammonium chloride and water.
$HCl+N{{H}_{4}}OH\to N{{H}_{4}}Cl+{{H}_{2}}O$
The white dense fumes observed are due to the formation of ammonium chloride.
So we can conclude that for the given solution, the assertion statement is true but the reason statement given does not support the assertion statement.

And among the given options the correct answer for the question is an option (c).

Note:
The fountain experiment is an experiment used to show the high solubility of polar gas. In ammonia fountain experiment, the ammonia gas is filled inside the whole flask and a few amount of water is injected inside the round bottom flask from the trough of water, the water dissolves the ammonia gas which lowers the pressure inside the flask and more water gets sucked inside the flask from the trough of water, creating a scenario similar to a fountain.