Do U mean my 1 coin will become two coins? I am giggling.
In a way, yes. In an unsuccessful hardfork, you will not have two coins on one chain,
but one coin on two viable chains. Both of these two separate chain coins will each
correspond to the same privatekey, that you control.
In the event of a hardfork that is 100% supported, then you will only have one viable coin.
The "two coins" only come about if "two chains" survive.
Will exchange give you two coins if your coin is in their address?
Depends on the exchange. See the policy of your exchange or ask them for clarification
in their support. They may be obligated by law within certain jurisdictions to provide you
both coins after a failed hardfork (two chain surviving fork). Some in some countries, may not.