The agents that easily break hydrogen bonds are

• A. Water
• B. Heat
• C. Water or Heat
• D. Salt

Answer: (C)

Hydrogen bonds are relatively weak attractions that can be disrupted by energy input or by a polar solvent. Water breaks hydrogen bonds because it is highly polar and can form new hydrogen bonds with molecules that were bound, effectively disrupting the original bonds. Heat provides the energy needed to overcome hydrogen-bond strength, allowing the molecules to separate. In hair, moisture or heat temporarily disrupts the interchain hydrogen bonds in keratin, enabling reshaping; as it dries or cools, new hydrogen bonds form to set the new structure. Salt doesn’t break hydrogen bonds as readily, since it mainly affects ionic interactions rather than directly disrupting hydrogen bonds. So, water or heat are the agents that easily break hydrogen bonds.