Basic doubt in options at expiry(multiple questions)

what is price at which an option expires ? is it the last traded price or price at which buyer stands ? does the buyer get a some money if the option expires at some price like 0.10 ?

Every out of money options expire at zero

Option are exercised on the closing price of the share/Index on the expiry day.

Lets says you have held INFY options 1000CE. So on expiry if the INFY Share close above 1000 then you are in the money, else you are out of the money. All OTM options do not get exercised hence their value is NIL. ITM options get exercised at the SPOT Price. So if INFY share price closes at 1010, then you are ITM by 10, hence the option exercise value will be Rs10.

However I’d like to add that the STT for exercising option is pretty high (0.125% of Contract Value). In your question you say if the price is 0.10, will you get money. Well if INFY would close at 1000.10 then yes you are 0.10 ITM, but you would also end up paying 0.125% STT which could be around 625 per lot.So Avoid exercising and square off before market closes.

could u explain it with some maths ?

Take a example that u have bought 8000 ce , one lot at 100 rs and nifty is trading at 7900, if nifty expires at 8000, all calls above 8000 will be zero, even ur 8000 ce become zero and same is the case with puts and remember one more thing as u bought 8000 ce for 100 rs , at the end of expiry u will be in profit only if nifty closes above 8100, because u have bought ce for 100 rs , so 8000+100=8100