How many polynucleotide strands are present in the structure of $RNA$ and $DNA$ respectively?

In $DNA$,uracil is replaced by

How many polynucleotide chains are present in the structure of $DNA$?

The $DNA$-histone complex can be removed from chromosomes by treatment with:

$t-RNA$ is also known as?

Assertion : $DNA$ is associated with proteins.
Reason : $DNA$ binds around histone proteins that form a pool and the entire structure is called a nucleosome.