7) Why are fuel cells considered a "clean" energy source? *

Hydrogen can be considered as a clean energy carrier similar to electricity. Hydrogen can be produced from various domestic resources such as renewable energy. ... Power generation,a hydrogen fuel cell generates electricity and gives off heat and water.

Alpha particles have positive charge, beta particles have negative charge, and answer 4 just doesn’t make sense. thus, you are left with only one possible answer.

The answer is a) carbon-12