Rent income on let out machinery to partnership firm

A Partnership Firm has income from ONLY  Machinery let out on Rent.

It has discontinued business activities!

1. Whether such rental income  (about 3 lacs per annum) should be shown under business income

or  income from other sources?

2.  Whether the firm is required to file assets and liabilities statement?

3. ITR Form No. to be used for filing Return

Thanks for your kind advice and support!

Regards,

Valerian DSouza