Which of the following nitrogenous bases is not found in $DNA$?

Which scientist proposed the concept of the Central Dogma?

Which of the following nitrogenous bases has a single-ring structure?

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:

The length of one full turn of a $DNA$ helix is:

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