Why is chromatin not condensed during interphase but is in prophase
Here's an image that explains the cell cycle:



And here's one that explains Mitosis as a subcategory of the cell cycle:



Chromosomes condense on the metaphase plate before they are pulled apart by kinetochore microtubules in a Tug-of-war. Chromosome condensation is not yet fully understood, but nucleosome structure is hypothesized to play a role. This is a very good question and is definitely not too broad.