Question

What is reserve resource ? Give example

Answer 1

the resources which are available and accessible but aren't yet being used properly and are conserved and used judicuously for the future. example :

river used for hydroelectricity

Answer 2

the resources which are available and accessible but aren't being used properly and are conserved and used judiciously for the future are called reserve resources. 
Example:- river water can be used to generate hydroelectric power.