can i do diploma in mechanical engineering after +2 science
The candidates who have passed class 10th or 12th can apply for admission to Diploma in Engineering .
But, as you've already completed your +2, it will be my advice to apply directly for a B. Tech instead of a Diploma.
Anyhow, after completing a degree in Diploma, you can go for B. Tech which will collectively take 6 years to complete your engineering (3 years diploma + 3 years B. Tech)
Hope this was helpful.