Private family foundation which supports corporations, trusts, community chests (united ways), funds or foundations organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, or for the prevention of cruelty to children; such persons as the directors deem proper, to be used for the benefit of poor, needy, and deserving persons to enable such persons to become self-supporting or to become more useful citizens; and such persons as the directors deem proper, to be used for the advancement or promotion of science, learning, medicine, surgery, literature, music, art or human welfare.