$(a)$ $A$ hydropower plant converts one form of energy into another. Name these two forms of energy.
$(b)$ State two advantages of generating hydroelectricity compared to the generation of electricity in a thermal power plant.

(N/A) Hydropower plants convert the potential energy of falling water into electrical energy.
$(b)$ Advantages of hydroelectricity over thermal electricity:
$(i)$ Hydropower plants use water to run the station,which involves no fuel cost,whereas thermal power plants require fossil fuels,which are costly.
$(ii)$ Hydropower plants do not cause pollution,whereas thermal power plants cause significant environmental pollution.