Q1. The answer is: the number of chromosomes double in interphase, not in mitosis.
Interphase is the phase in the cell cycle during which cells that undergo mitosis prepare for division. In interphase, DNA of the cell copies, so this is when the number of chromosomes double. After that cell undergoes mitosis and divide on two identical.
Q2. The answer is anaphase.
Duplicated chromosome has two sister chromatids, which are identical copies of the chromosome. In anaphase, the sister chromatids separate from each other to the opposite sides of the cells. From that moment, each chromosome is half of what it just was.
Q3. The answer is telophase and cytokinesis.
After sister chromatids are separated and moved to the opposite sides of the cell, telophase and cytokinesis take place. Membrane forms around each set of chromosomes on two opposite sides of the cells (telophase) and cell divides into two identical daughter cells (cytokinesis)
