Potassium(k)=1s22s22p63s23p64s

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.

The velocity would be 2 

The se-ci  bonds is more polar  than s-br bond

The higher the temperature, the increased rate constant for a reaction.(positive linear association)