With which nitrogenous base does cytosine pair?

In a $DNA$ fragment containing $6$ adenine nitrogen bases,what is the number of thymine nitrogen bases?

Given below are two statements:
Statement $I$: In prokaryotes,the positively charged $DNA$ is held with some negatively charged proteins in a region called nucleoid.
Statement $II$: In eukaryotes,the negatively charged $DNA$ is wrapped around the positively charged histone octamer to form nucleosome.
In the light of the above statements,choose the correct answer from the options given below:

What is present at the $5'$ end of the sugar in a polymer of nucleotides?

In $B-DNA$,one full turn of the helical strand contains

How many polynucleotide chains are present in $DNA$?