Hi Pooja,

It is believed that scoring 60-70% in 10th is likely good. For taking admission into science stream, the eligibility criteria is set by the college itself. In whichever college you want to get admission kindly contact to the college itself for further details.

No, there is no entrance exam for many colleges, but again it depends on the college itself whether they are conducting any entrance exam for admission or not. Kindly check before you take admission in any college or in any state.

I hope this helps.