The bond between the phosphate group and the hydroxyl group of sugar is........

In the structure of a dinucleotide,between which carbons of the sugars of two consecutive nucleotides is the phosphodiester bond formed?

$DNA$ exists in a double-stranded form whereas $RNA$ is mainly a single-stranded molecule. What is the likely reason for $DNA$ being double-stranded?

Which of the following nitrogen bases is found only in $DNA$?

Coliphage $T_2$ has

Which one of the following can form a nucleotide of $DNA$?