The council of any city or town that alters and rearranges its boundary lines so as to absorb two or more cities or towns may exempt from taxation for a period not exceeding five years any industrial or manufacturing plant situated in the territory added to said city or town, but said terms of exemption shall not be renewed or extended.
The council of any city or town may also exempt from taxation for a period not to exceed 10 years any industrial or manufacturing plant that may be established in said city or town; provided, that said term of exemption shall not be renewed.