Question

The surface of water in a lake is just going to freeze. Then the temperature of water at the bottom of the lake is :

• A. $4K$
• B. ${277}^{0}C$
• C. $277K$
• D. ${100}^{0}C$

Answer 1

The correct option is C $277K$

Water achieves its maximum density at roughly $4^{o}C$ i.e. at $277K$

density of water above and below $277K$ is less than maximum density as shown in the fig. hence below this temperature density of water decreases i.e. water just goes to freeze.

Hence if surface of water just going to freeze then the temperature of water at the bottom of the lake is $277K$.