Which list includes elements with the most similar chemical properties?

a) br, ga, hg
b) cr, pb, xe
c) o, s, se
d) n, o, f

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.