Many clients want to know if they can keep a credit card and not list it when they file a Chapter 7 bankruptcy. You must list everyone that you owe money to, there are no exceptions. However if you have a zero balance on a credit card, you don't owe that creditor any money. But most major credit card companies receive notice of bankruptcy filings even if they are not listed. They will close any open credit card accounts even if the account is a zero balance.
You are better off getting a new credit card after your Chapter 7 bankruptcy to use for emergencies.