What are the causes of pimples n acne? What is the permanent solution and preventation of the same.

You might have a zinc deficiency. My son greatly improved his skin as a teen by taking 25 mg. of zinc gluconate three times a day and, over a month's time, working his way up to six tablets per day.

Are you following good and proper methods of cleansing, etc.

Taking a balanced diet, a sufficient amount of water intake will help to get rid of acne.
Refer the below link for more details,

15 ways to get rid of acne