Answer:
The sample a which is solid at 20°C is "Iodine"
The sample b which is liquid at 20°C is "Bromine"
The sample c which is gas at 20°C is "Chlorine"
Explanation:
Iodine : It starts melting at 113.7°C, so the solid sample found is the iodine. Iodine is present in both solid as well as in vapor state. Basically it is kept in closed jars. Only when it reaches the temperature above the melting point is starts melting.
Bromine: It is a non metallic element that is present in the liquid state, being a member of halogen group. It is heavy, mobile and dangerous reddish brown liquid. It is corrosive in nature, when comes in contact with human tissue and causes irritation in eye when comes in contact with its vapor.
Chlorine: In room temperature it is gas, as it has weak intermolecular interaction which fails to keep the molecules closely attached.
