Which elements do hydrogen fuel cells combine to produce electricity?

(! ) what’s fracking and what does it have to do with carbon, carbon dioxide, or fossil fuels?

How is the national wildlife refuge system similar to the pacific region coastal program? a. both programs are concerned with providing habitats for wildlife b. both programs are primarily concerned with preserving fish species c. both programs have set aside 150 million acres of land d. both programs are under the u.s. fish and wildlife service

What is the ecological role of food chains and food webs