Repetitive $DNA$ is separated from bulk genomic $DNA$ by which of the following techniques?

Which one of the following histones is not present in the core particle of the nucleosome?

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:

In $DNA$,the complementary bases are,

In eukaryotic chromosomes,the association of $DNA$ with histone and non-histone proteins was reported by . . . . . . in $1974$.

Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?