Chemical involve the breaking and making of chemical bonds. 1)sometimes 2)always. 3) never

Chemical changes always involve the breaking and making of chemical bonds.

Explanation:

In chemical changes, the atoms regroup to form new substances. As the first law in Thermodynamic says, "energy cannot be created or destroyed"

Option 2 Always is the Answer

Explanation:

Breaking of bonds requires energy. Absorption of energy takes place to break a bond.

Formation of a bond results in the release of energy.

Hence breaking of bonds is an endothermic process and formation of a bond is exothermic.

The enthalpy of a reaction or the Heat energy of a reaction is given by  

stands for energy of products

stands for energy of reactants

If  then ∆H will be Positive and the reaction is Endothermic

If then ∆H will be Negative and the reaction is Exothermic

the answer is 0.8m.

by: nicholas