Which is a bicyclic base?

Which one is found in $ATP$ ribonucleotide?

Which of the following is not a constituent of nucleic acids?

If the sequence of bases in one strand of $DNA$ is $CTGTCAGTA$,then the sequence of bases in its complementary strand is

In $DNA$,the base units are linked by which of the following?

Hydrolysis of which of the following nucleic acids does not give an equal number of $A$ and $T$ or $G$ and $C$?
$(A)$ $m$-$RNA$
$(B)$ Single strand $DNA$
$(C)$ $r$-$RNA$
$(D)$ Double helix $DNA$