Hello Harshdeep

For admission to diploma in Engineering in Polytechnic College, eligibility criteria is candidate should have completed Class 10th or its equivalent examination from an approved Board.
If you are seeking admission directly in third semester under lateral entry scheme, you will have to contact the college authorities as not all colleges have provision of lateral entry.

And yes, you should revise the concepts of Maths and science of Class 10th it would be helpful for you.

Good luck!