Business income as trust property: exemption depends on incidental purpose and separate accounts; concealed income forfeits exemption. Income from a business carried on by a charitable, religious or educational trust may be treated as property held under trust and exempt under section 11 if the business is incidental to the trust's objects and separate books are maintained; exemption is unavailable for any concealed income, and where the Assessing Officer determines income in excess of books, that excess is deemed applied to non-charitable or non-religious purposes.