Nucleolus and nuclear membrane disappear during

In a eukaryotic cell,during which phase does the synthesis of histone proteins occur?

$A$ student was asked to identify a permanent slide of mitosis. He made the following observations:
$(i)$ Splitting of centromere and formation of daughter chromatids.
(ii) Chromatids are migrating towards the opposite poles.
The stage would be

The disappearance of the nuclear envelope and nucleolus,accompanied by the condensation of chromatin into chromosomes,is a characteristic feature of which phase of mitosis?

Which of the following structures serves as the site of attachment for spindle fibers?

During the $G_2$-phase,the amount of $DNA$ in a diploid cell is equivalent to which of the following?