Why do chromosomes often appear with an X shape in diagrams and in photos taken through a microscope

In photos taken through a microscope, chromosomes may appear to be in the shape of an X. This is because in the middle of the chromosome, there are two strands bonded together, called the centromere. Hope this helps ;)

True statement gravity force is more on bigger mass, less on smaller mass.all mass fall on planet with same acceleration and speeds

Yes yes yes very good