In looking at the entire declaration of independence, what are ten of the most important concepts that we might expect to be included in the constitution that would be written in 1787?

Which of these is a disadvantage of hydrogen fuel cells? a. engines that use hydrogen fuel are more efficient than gasoline-powered engines. b. the only emission produced by hydrogen fuel cells is water. c. hydrogen fuel is continually available and useful for heating. d. hydrogen fuel is often purified in a process that emits lots of greenhouse gases.