$D_2O$ is used more in

Which of the following statements does not define the characteristic property of water,"Water is a universal solvent"?

Why is water used as a medium for chemical reactions?

Given below are two statements:
Statement-$I$: Permutit process is more efficient compared to the synthetic resin method for the softening of water.
Statement-$II$: Synthetic resin method results in the formation of soluble sodium salts.
In the light of the above statements,choose the most appropriate answer from the options given below:

The hardness-producing salt whose solubility in water decreases with a rise in temperature is

Explain the importance of water for living organisms.