Which of the following features provide stability to the helical structure of $\text{DNA}$?

When did Watson and Crick propose the $DNA$ double helix model?

The double helix model of $DNA$ was proposed by

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 the similarity between $DNA$ and $RNA$?

Provide definitions/explanations for the following terms: $Nucleosome$ and $Euchromatin$.