1. in a compound, chemical energy is contained in the (1 point)
a. nuclei of the atoms.
b. unbonded electrons.
c. bonds.
d. movement of the electrons.
2. which of the following statements is true about what happens during a chemical reaction? (1 point)
a. bonds of the reactants are broken, and bonds of the products are formed.
b. bonds of the reactants are formed, and bonds of the products are broken.
c. the bonds of both the reactants and the products are broken.
d. the bonds of both the reactants and the products are formed.

1. Potential of a chemical substances to undergo transformation in a chemical reaction is known as chemical energy. The chemical energy is stored in the bonds of chemical compounds.

Hence, in a compound, chemical energy is contained in bonds.

2. The process in which one or more substance known as reactants are converted to one or more completely new substances known as products are formed is known as a chemical reaction.

Hence, during a chemical reaction bonds of the reactants are broken, and bonds of the products are formed.

1.C 2.A are the answer to the following questions.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol