What are the disadvantages of fossils fuels?

What are the disadvantages of solar cells.

What are the disadvantages of nuclear power plants?

What are the disadvantages of generating hydroelectricity ?

Write three disadvantages of friction.

What are the advantages of using CNG and LPG as fuels?

What are the advantages and disadvantages of crystallization over evaporation?

What are the advantages and disadvantages of using a solar cooker ? Are there places where solar cookers would have limited utility?