What if after buying an option at say rs 15 it beomes 0 and then from 0 it beomes rs 50 at expiry so will i get rs 35 profit?


Yes, you will if you hold that option till expiry.

Yes, you will get Rs.35 profit.

If it is 1 lot of nifty, then nifty lot size = 50, so you will get 50x35 = 1750 as profit per lot.

Yes profit of Rs. 35 x Lot Size