Trust is required to file a return when Income before claiming exemption U/S 11 is more than basic exemption limit.instead of considering profit, consider "Income" to check whether trust is required to file return or not..
Trust is not obliged to file ROI,when its business income is Rs.1 lac,as this income is to be assessed as business income and basic exemption limit is Rs.1,80,000/-, provided there is no other income of the trust.