Which of the following elements is a member of the halogen family and is located in period 3? *

Hey!
This would be chlorine.
Period refers to rows, and the halogen family is group 17, they have 7 valence electrons.

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.

Ithink the answer is d