In which of the following processes is it necessary to break covalent bonds as opposed to simply overcoming intermolecular forces?
a. melting mothballs
b. dissolving hydrogen bromide gas in water to form hydrobromic acid
c. vaporizing ethyl alcohol
d. changing ozone to oxygen gas

D. Changing ozone to oxygen gas

Explanation:

As a rule of thumb, it is always noting that making putting a substance through physical changes like melting or boiling, evaporating involves breaking intermolecular bonds. On the other hand, making a substance undergo chemical changes involves breaking intramolecular bonds like ionic bonds and covalent bonds.

Oxygen being changed from ozone to oxygen is a chemical change and therefore requires breaking of the oxygen-oxygen double bonds

aquifers are bounded above and below by impermeable rock. the driving force of groundwater movement in confined aquifers is pressure, rather than gravity.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.