Question

chemical reactions:
a always release energy
b always absorb energy
c can either absorb or release energy
d are never accompanied by energy changes

Explanation:

• Option a: Incorrect. Some chemical reactions (endothermic) absorb energy, not always release.
• Option b: Incorrect. Exothermic reactions release energy, so not always absorb.
• Option c: Correct. Chemical reactions can be exothermic (release energy) or endothermic (absorb energy).
• Option d: Incorrect. Chemical reactions involve bond breaking/forming, which always have energy changes.

Answer:

c. can either absorb or release energy