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Question: **Assertion (A):** Ice floats on water. **Reason (R):** Ice has lower density than water at 4°C....

Assertion (A): Ice floats on water.

Reason (R): Ice has lower density than water at 4°C.

A

Both A and R are true and R is the correct explanation of A

Answer

Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).

Explanation

Solution

  1. Evaluate Assertion (A): Ice floats on water. This statement is a well-known observation and is scientifically true.

  2. Evaluate Reason (R): Ice has lower density than water at 4°C. The density of ice is approximately 0.917 g/cm³. Water exhibits anomalous expansion, reaching its maximum density of 1.000 g/cm³ at 4°C. Since 0.917 g/cm³ < 1.000 g/cm³, ice is indeed less dense than water at 4°C. Therefore, this statement is also true.

  3. Check if Reason (R) is the correct explanation for Assertion (A): An object floats on a liquid if its density is less than the density of the liquid. Because ice has a lower density than water (even at water's maximum density at 4°C), it floats on water. Thus, Reason (R) provides the correct explanation for Assertion (A).

The lower density of ice compared to water is due to its open, cage-like crystalline structure formed by hydrogen bonding, which results in a larger volume for the same mass compared to liquid water.