Solution:Concept: The only non-metal that is liquid at ambient temperature is bromine (Br). Other than mercury, it is one of only two elements on the periodic table that is a liquid at ambient temperature. On the other hand, mercury (Hg) is a metal.
Bromine is found to be the non-metal that is liquid at room temperature and it is represented as Br. This is due to the fact that the intermolecular forces are strong enough so that it does not evaporate.
Bromine is able to form diatomic molecules and Van der Waals interactions are highly strong.
The volatility of bromine is responsible for its very penetrating, choking and unpleasant odour. Whereas, the other halogens are gases.
Hence, the correct answer is option 2.