Which of the following is not present in nucleic acids?

Which statement is correct for the nucleotides of $DNA$?

The number of complementary hydrogen bond$(s)$ between a guanine and cytosine pair is

The total number of hydrogen bonds in a $DNA$ double helix strand,where one strand has the following sequence of bases,is $...........$
$5^{\prime}-G-G-C-A-A-A-T-C-G-G-C-T-A-3^{\prime}$

Which among the following is a double ring containing nitrogen base present in nucleic acids?

The double-helical structure of $DNA$ is due to ....