I have setup my own quorum blockchain network. If I deploy an ERC20 token contract with a coin name (say ABC), will I be able to list the coin in exchanges ?
In theory, yes. But the chances for that to happen are next to nothing.
For an exchange to accept your coin they would have to:
1) Trust your blockchain that it's fair, valid and uncompromisable
2) Run their own node in your blockchain (they certainly don't want to trust your or somebody else's nodes even if they trust the blockchain)
3) Evaluate your coin to have enough liquidity and interest to be worth it. This is highly unlikely as it's only available in a private blockchain (yours).