How many nucleotide pairs are present between two adjacent nucleosomes?

Read the following statements and choose the set of correct statements:
$(a)$ Euchromatin is loosely packed chromatin
$(b)$ Heterochromatin is transcriptionally active
$(c)$ Histone octamer is wrapped by negatively charged $DNA$ in nucleosome
$(d)$ Histones are rich in lysine and arginine
$(e)$ $A$ typical nucleosome contains $400 \ bp$ of $DNA$ helix
Choose the correct answer from the options given below:

How many polynucleotide chains are present in $DNA$?

The purine nitrogen bases in $DNA$ are .....

$A$ $DNA$ fragment contains $12$ nucleotides. What is the ratio of purine and pyrimidine nitrogenous bases in it?

What is the similarity between $DNA$ and $RNA$?