DISILLUSIONED OF PARTNERSHIP FIRM

As per schedule 1 of cgst act Permanent transfer or disposal of business assets where input tax credit has been availed on such assets are supply even made without consideration.
But as u clarified that partnership firm had adopted composition scheme so they not availed itc so in my opinion so liability will arise now at the transfer of assets under gst.

what will happen with closing stock..?

Sir as per law language only asset is written in schedule 1 so in my opinion both capital assets as well as business asset are covered there.

If Firm is Dissolutioned then the Partner's share transfer to Partners Capital account and No more tax liability in any of the view.
Partner can introduce as Capital in his Proprietary Business.