Which functional group is present in carboxylic acid?

Which of the following are the heteroatoms present in $CH_{3}-CH_{2}-O-CH_{2}-CH_{2}Cl$?
$(i)$ Oxygen
$(ii)$ Carbon
$(iii)$ Hydrogen
$(iv)$ Chlorine

What is the difference between two consecutive members in a homologous series of alkanes in terms of:
$(i)$ molecular mass.
$(ii)$ number of atoms of elements.

What are biochemical catalysts called?

What is the molecular formula of propanone (acetone)?

Draw the electron dot structure of ethane,$C_{2}H_{6}$.