Each bond or other evidence of indebtedness shall contain on its face a statement of the purpose for which the same is issued and no officer of the city shall use the proceeds thereof for any other purpose, except that whenever the proceeds of any bond issue, or a part thereof, remain unexpended and unencumbered for the purpose for which said bond issue was made, the council may authorize the use of such unexpended and unencumbered funds subject to the approval of the Michigan Municipal Finance Commission where required:
(a) For an additional extension or improvement of facility or project for which the bond issue was made.
(b) For the retirement of such bond issue.
(c) If such bond issue has been fully retired or funds are segregated which are adequate for such purpose, then for the retirement of other bonds or obligations of the city.
(d) If there is no other indebtedness, or funds are segregated which are adequate for such purpose, then for such other purposes as may be permitted by law.