Which of the following nitrogen bases,either of purine or pyrimidine,does $NOT$ contain an $-NH_2$ group attached to its ring?

Assertion $(A)$: Adenine and guanine are present in $RNA$ as purine bases.
Reason $(R)$: The base uracil is present in $RNA$.
The correct option among the following is:

Which of the following statements is incorrect regarding the structure of nucleic acids?

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

Given below are two statements:
Statement $I$: $A$ unit formed by the attachment of a base to $1'-$position of sugar is known as nucleoside.
Statement $II$: When nucleoside is linked to phosphorous acid at $5'-$position of sugar moiety,we get nucleotide.
In the light of the above statements,choose the correct answer from the options given below:

Adenosine is an example of which of the following?