How many hydrogen bonds are present between Guanine and Cytosine?

If a double stranded $DNA$ has $20$ percent of cytosine,calculate the percent of adenine in the $DNA$. (in $\%$)

The segment of $DNA$ which acts as the instrumental manual for the synthesis of the protein is:

$DNA$ consists of two complementary nucleotide chains. If the sequence of nucleotides in one of the chains is $AGCTTCGA$,then the nucleotide sequence in the other chain shall be:

Identify $A, B$ and $C$ in the given diagram:

$E. coli$ bacterium possesses a single large circular $DNA$ as its genetic material. This strand codes for: