No real property shall be purchased, acquired, sold, or given away by the City whether within or without its corporate limits except upon the affirmative vote of five-sevenths (5/7) of all the Councilors elect after a public hearing called for the purpose of considering such proposal to purchase, acquire, sell, or give away real property. Notice of such hearing shall be given by publication in a newspaper circulated within the City, once in each week for two (2) consecutive weeks, the last publication to be not more than three (3) days before said hearing. Provided, however, that nothing herein contained shall prohibit the City Council from leasing any real property owned by the City and not needed for municipal purposes for a period not longer than ten (10) years and upon the affirmative vote of four-sevenths (4/7) of the Councilors elect, nor prohibit the use of such real property for purposes beneficial to the City. Provided further that no park or cemetery, as legally described upon adoption of this Charter, may be sold by the City unless approved by majority of the electors voting thereon at any general or special election.