During which phase does $DNA$ replication occur?

Can there be $DNA$ replication without cell division?

Select the correct statements regarding $S$-phase of interphase:
$I.$ Occurs between $G_{1}$ and $G_{2}$ phases.
$II.$ $DNA$ replication begins in the nucleus.
$III.$ Centrioles duplicate in the cytoplasm.
$IV.$ As $DNA$ is doubled,the number of chromosomes also doubles.
The option with correct statements is:

The $S-$phase of the cell cycle is characterized by

If an egg of an organism has $10 \; pg$ of $DNA$ in its nucleus,how much $DNA$ would a diploid cell of the same organism have in the $G_2$ phase of the cell cycle (in $; pg$)?

In the $S$ phase of the cell cycle: