if i start now for the exam will i get a chance to be in a good college

Hello,
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The Matter is not about when you started your preparation. It totally matters the percentage you score and the Institute you choose.
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If you score minimum of 550 to 600+marks you will not face any kind of problem in admission even if you apply for top universities of India, Because scoring 600+ is not that easy and if you score you will be given 1st preferance Because you will be in merit list.
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Now if you belong to SC/ST you need minimum of 400+  score to get Admission in best colleges.
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If you just want a seat rather then best Institutes then your score must be in between 400 to 500+.
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So, firstly prepare well and score high percentage. And the remaining problems will automatically gets solved. Best of luck