Re: Is "isn't there?" as a question tag commonly used?
There isn't enough food for all of us, is there?
There is enough for all of us, isn't there?
The two sentences above contain the standard question tags and they are used almost all the time.
Your suggested version is possible but only when someone is expressing disbelief.
John: There's enough food for all of us.
Tim: Are you sure?
John: Yes, just take a look in the kitchen.
Tim (a few minutes later): I just looked in the kitchen and I could only find two potatoes, a bag of rice and an onion.
John: That's right. That's what I bought.
Tim: Oh! So there's enough food for all of us, is there? You are totally wrong - there are twelve people. That amount of food is definitely not enough.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.