Is it possible for 2 different elements to have the same atomic number

No.

Explanation:

No. The atomic number  is the number of protons in the nucleus and the number defines what element it is.   If a proton is lost it becomes a different element with a different atomic number.

answer; i do believe the correct answer is (river); /// good luck

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.