Question

Assertion :When liquid water is cooled, it contracts until a temperature of approximately 4 degrees Celsius is reached. After that, it expands slightly until it reaches the freezing point. Reason: The distance between the H-O bond is more than the O-O attraction in the water. Hence, the water freezing over into ice is held together not by the O-O attraction but by the H-O attraction.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Both Assertion and Reason are incorrect

Answer 1

Answer: (A)

Assertion
When liquid water is cooled, it contracts until a temperature of approximately 4 ${}^{o}C$ is reached. After that, it expands slightly until it reaches the freezing point.

Reason
The distance between the $H-O$ bond is more than the $O-O$ bond in the water. Hence, the water freezing over into ice is held together not by the $O-O$ attraction but by the $H-O$ attraction.

Hence, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

The density of water is maximum at 4 ${}^{o}C$.

The density of water decreases when you cool it from 4 ${}^{o}C$ to 0 ${}^{o}C$.

Hence the correct option is A.