Why do you want to achieve Ph.D.(in graduate program)?What relevant experience you think you have in research academics prior to jobs?

The following questions must be answered in the personal statement
1) Why do you want to achieve Ph.D.(in graduate program)?
2) why you are interested in this university?
3) What relevant experience you think you have
in research academics prior to jobs?
4) Why do you think you will be successful in the topic?