In one nucleosome,which one of the following histone molecule is $NOT$ double?

$DNA$ sequences that code for proteins are known as:

Which of the following statements is true for $DNA$?

Identify the correct matching for Euchromatin and Heterochromatin from the given statements:
$I -$ Loosely packed
$II -$ Densely packed
$III -$ Darkly stained region
$IV -$ Lightly stained region
$V -$ Transcriptionally active chromatin
$VI -$ Transcriptionally inactive chromatin
Euchromatin $\quad\quad$ Heterochromatin

The octamer that forms a complex unit with $DNA$ is called:

If the percentage of Adenine is $30\%$,then what would be the percentage of Guanine (in $\%$)?