Hi Harikesh,
                      Yes definitely, you can do diploma. Apart from failed in 12th, as you're from science background, this will help you a lot in your diploma, things will be easier to you.

So, what ever the entrance exam is there in your state, apply for it & prepare well that you can get good reputed government colleges. Just keep it in your mind, college matters a lot. So, work hard as much as you can to get into a good government colleges. That will also help you in placement.

Also in those days diploma engineers are in high demand in government ferms.

So, you don't be upset, life is all about hardles. Go for diploma..

Good luck!

Hello,

The basic eligibility criteria for diploma course is that you must have passed your 10th from a recognised board. Therefore it has nothing to do with your 12th percentage whether you have passed it failed in 12th, it is not going to affect your admission process for diploma course.
So, yes you can apply for diploma first year.

Best of luck.