The Council shall, upon petition of qualified registered electors equal in number to not less than thirty-five per centum of the votes cast at the last municipal election at which all qualified registered electors were entitled to vote, submit as separate questions, by ordinance, to the qualified registered electors of the city, at any special election at which all qualified registered electors are entitled to vote, a plan for the acquisition of one or more public utilities and its adoption and the issuance of bonds of the city for the payment therefor. (Amended April 21, 1941)