In the structure of $DNA$,if one nitrogenous base is Guanine,which nitrogenous base pairs with it?

Describe the structure of a polynucleotide chain of $DNA$ or $RNA$.

$A$ $DNA$ polymer has a free phosphate group at one end of the sugar,which is called the $P$ end of the polynucleotide chain. Similarly,at the other end of the polymer,there is a free $OH$ group of the sugar,which is called the $Q$ end of the polynucleotide chain.
$\quad P \quad Q$

Which of the following statements is incorrect regarding the $DNA$ model proposed by Watson and Crick?

Why are histone proteins positively charged?

Which of the following statements are correct with reference to the packaging of the $DNA$ helix?