What is the unit of base-sugar-phosphate in nucleic acids called?

Among the following compounds,which one is found in $RNA$?

Which base is present in $RNA$ but not in $DNA$?

Given below are two statements:
Assertion $(A)$: Hydrolysis of $DNA$ does not form equal number of $A$ and $T$; $G$ and $C$.
Reason $(R)$: In $DNA$,adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine.
The correct answer is:

How are nucleotides linked together in nucleic acids?

Hydrolysis of nucleic acid gives nitrogenous base,sugar and......