Question

Which of the following has pungent odour?
(A) $ {{H}_{2}}S{{O}_{4}} $
(B) $ C{{H}_{3}}COOH $
(C) $ HCl $
(D) Both a and b

Answer 1

Hint: HCl is a colorless liquid with a pungent irritating odor. Pungent materials have a strong, sharp smell or taste which is so strong that one feels uncomfortable. Pungent odor is very irritating to the nose. Sulfuric acid can also have pungent odor but only when it is heated but in case of HCl irritation and unpleasant smell can be easily felt without heating.

Complete Step by Step Solution
 $ {{H}_{2}} S {{O}_{4}} $ is a colorless or sometimes dark brown oily liquid. It is odorless without heating and on heating has a pungent smell. $ C {{H}_{3}} COOH $ (Acetic acid) has heavy vinegar like odour. HCl has a very strong unpleasant and irritating smell. It is pungent in odour.
So, the correct option is (C).

Additional Information
Hydrochloric Acid: It is a very stable compound but decomposes at high temperatures into hydrogen and chlorine. HCl shows violent reactions with bases. It also reacts violently with oxidants forming toxic chlorine. On air contact it emits corrosive fumes. HCl attacks nearly all metals thereby releasing hydrogen gas.
Sulfuric Acid: Cold $ {{H}_{2}} S {{O}_{4}} $ reacts with most of the metals and the reactivity increases with temperature. The acid can release flammable hydrogen gas when in contact with metals. $ {{H}_{2}} S {{O}_{4}} $ is highly corrosive in nature due to which it has a highly exothermic reaction with water. It is an excellent dehydrating agent.

Note
Acetic acid also called ethanoic acid is the most important of the carboxylic acids. A dilute solution of acetic acid produced by fermentation and oxidation of natural carbohydrates is called vinegar. Acetic acid is used in the preparation of metal acetates used in making photographic films and textiles and volatile organic esters.