Which of the following is the use of propanone?

$CH_{3}COOCH_{3}$ is the molecular formula of which compound?

Ethanoic acid can be obtained from ethanol by the process of:

Mention the functional group which always occurs at the terminal position of a carbon chain of an organic compound.

An atom of an element contains six electrons in its valence shell. This element is the second major component of air. It exists as a diatomic molecule.
$(i)$ Identify the element.
$(ii)$ Show the bond formed between two atoms of this element.
$(iii)$ Write the nature of the bond between the two atoms.

Why is hard water not suitable for washing clothes with soap?