Which substance is not present in nucleic acid?

$A$ nucleic acid,whether $DNA$ or $RNA$,gives on complete hydrolysis,two purine bases,two pyrimidine bases,a pentose sugar,and phosphoric acid. Nucleotides,which are intermediate products in the hydrolysis,contain:

The $AT/GC$ ratio in human beings is (where $A = \text{adenine}$,$T = \text{thymine}$,$G = \text{guanine}$,$C = \text{cytosine}$)

The presence or absence of a hydroxyl group on which carbon atom of the sugar differentiates $RNA$ and $DNA$?

The sequence in nucleic acids is .......

In the sugar that differentiates $RNA$ from $DNA$,the presence or absence of the $-OH$ group occurs at which carbon atom?