The total number of atoms represented by the formula fe3(po4)2 is a. 11 b. 12 c. 13 d. 15

C.

Explanation:

We have to keep in mind for this question that we have to take into account the subscripts.

The subscript will affect only the number in the left, so the first part would be:

In this part we will have 3 iron atoms. Then we will have:

In the we will have 1 atom of P and 4 atoms of O. (When we dont have any number as subscript we have to assume that we have a "1")

Then we have a "2" out side the the parenthesis , so we have to multiply by "2" all the atoms inside the parenthesis, so:

1 atom of P x 2 = 2

4 atoms of O x 2 = 8

So, in total we will have:

3 atoms of Fe + 8 atoms of O + 2 atoms of P = 13 atoms

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.