Which of the following non-metal exists in liquid state at room temperature?

Bromine

The correct answer is option 3. Bromine.

Out of the listed non-metals, the one that exists in a liquid state at room temperature is Bromine (Br).

Chlorine (Cl):  Chlorine is a gas at room temperature.

Fluorine (F):  Fluorine is also a gas at room temperature.

Bromine (Br):  Bromine is a reddish-brown liquid at room temperature, making it the only non-metal on this list that exhibits this property.

Iodine (I):  Iodine is a solid at room temperature, although it sublimates easily, meaning it transitions directly from solid to gas without becoming a liquid.