Heavy water $(D_2O)$ is used as:

Which of the following reagents is not used for the removal of permanent hardness of water?

Write two reactions to explain the amphoteric nature of water.

In the charring process, concentrated sulfuric acid reacts with sugar to give sugar charcoal. What is the role of conc. $H_2SO_4$ in this reaction?

What properties of water make it useful as a solvent? What types of compounds can it $(i)$ dissolve and $(ii)$ hydrolyse?

Which one of the following is used for reviving the exhausted permutite?