Which one of the following bases is $not$ present in $DNA$?

In nucleic acids,the sequence of the backbone components is

If one strand of $DNA$ has the sequence $ATGCTTGA$,what would be the sequence of its complementary strand?

Uracil is a base present in $RNA$ with the following structure. The percentage of $N$ in uracil is $............$.
Given:
Molar mass $N = 14 \, g \, mol^{-1} ; O = 16 \, g \, mol^{-1} ; C = 12 \, g \, mol^{-1} ; H = 1 \, g \, mol^{-1}$.

The number of hydrogen bonds between guanine and cytosine; and between adenine and thymine in $DNA$ is

$RNA$ is different from $DNA$ because it contains ...