Question

Which of the following is a basic gas?
A. HCl
B. \[N{H_3}\]
C. \[C{O_2}\]
D. NO

Answer 1

Hint: To solve this question it is important to understand what pH is. pH is the measure of the acidic or basic strength of the compound. If pH is less than 7 then the compound is acidic in nature. If the pH is more than 7 then the compound is basic in nature and if pH is equal to 7 then the compound is neutral. Among the given options the basic gas is highly soluble in water and it has a strong pungent choking odor.

Complete step by step solution:
Let us consider all the options and find out the basic gas.
Hydrochloric acid (HCl) gas is a strong acid. This gas is a highly corrosive and toxic colourless gas that forms white fumes on contact with humidity. So, option A is not a basic gas.
Ammonia (\[N{H_3}\]) is an alkali gas. As we know, soluble bases are known as alkali. Ammonia gas when dissolved in water forms ammonium hydroxide (\[{NH_4}OH\]) which is an alkali. It is an irritant and has pungent odour and is widely used in industry. Which upon inhalation, is deposited in the upper airways and causes irritation also causes eye irritation. So, option B is the correct one.
Carbon dioxide (\[C{O_2}\]) gas when dissolved in water produces an acidic solution of carbonic acid (\[{H_2}{CO_3}\]). The acidity of water can be reduced by a base such as baking soda. So, option C is not a basic gas.
Nitric oxide (NO) is an acidic colourless and non-combustible gas which when dissolved in water produces an acidic solution of nitrous acid (\[{HNO_2}\]). So, option D is not the correct one.
So ammonia is a basic gas. Hence the correct option is (B).

Note: Always remember that these gases can only be acidic and basic when they are dissolved in water. Acidic gases produce acids in water while basic gases produce bases or alkalis in water.