What occurs in a chemical reaction?
a. products are formed without chemical bonds being broken.
b. products are formed from reactants by the breaking and forming of new bonds.
c. reactants are formed without chemical bonds being broken.
d. reactants are formed from products by the breaking and forming of bonds.?

Option (b) is the correct answer.

Explanation:

A reaction due to which there occurs a change in the chemical composition of a substance is known as a chemical reaction.

This change in chemical composition occurs when bonds between reactants are broken to form products with new bonds.

Thus, we can conclude that in a chemical reaction products are formed from reactants by the breaking and forming of new bonds.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

if you're asking what comes out, it's steam.