_______ is a greenish yellow gas having an irritating choking and unpleasant odour.A. FluorineB. BromineC. ChlorineD. Hydrogen sulphide

The correct answer is C. Chlorine.

Explanation:

Chlorine is a greenish-yellow gas at room temperature, known for its strong, irritating, and choking odor. It has a pungent smell that is quite unpleasant and can cause discomfort when inhaled, often leading to coughing or difficulty breathing.

Chlorine is commonly used in disinfectants, bleach, and water purification processes because of its ability to kill bacteria and other pathogens. However, exposure to high concentrations of chlorine gas can be harmful, leading to respiratory problems, throat irritation, and in severe cases, lung damage.

Option A: Fluorine is a pale yellow gas, but its odor is not as well known as chlorine's.
Option B: Bromine is a reddish-brown liquid at room temperature with a strong, unpleasant odor, but it is not a gas.
Option D: Hydrogen sulphide is a colorless gas with a characteristic smell of rotten eggs, but it is not greenish-yellow.
Thus, the correct answer is Chlorine (C).