B.Sc Chemistry

I think the first criteria for admission in any college is that you have passed 12 th exam. And there are compartment exams if anyone fails in one or two exams. 

So first give that, pass it and then you can try for admission. 

Now a days for central universities, you have to appear for CUET Ug exam conducted by NTA. For state Universities either they conduct their own exam or they take on the basis of cuet. You can check the websites of the nearest state University you want to get admission. 

In private colleges you can get directly admission without any exam. You can also check good colleges. 

It is possible, but it depends on the university rules and your time management skills. If one course is regular and the other is through distance learning (open mode), then you can pursue DMLT and BSc Chemistry together.
However, doing two full-time regular courses at once is generally not permitted. It's better to prioritize one if you want in-depth knowledge and better academic performance.