Given a scientific passage and an answer, generate a question for the given answer.

[EX Q]: Passage: Amphibians have permeable skin that easily absorbs substances from the environment. This may explain why they seem to be especially sensitive to pollution. Monitoring the health and survival of amphibians may help people detect pollution early, before other organisms are affected. Answer: amphibians
[EX A]: What group of animals has permeable skin that makes them vulnerable to pollution?

[EX Q]: Passage: Nuclear changes occur with a simultaneous release of energy. Where does this energy come from? If we could precisely measure the masses of the reactants and the products of a nuclear reaction, we would notice that the amount of mass drops slightly in the conversion from reactants to products. Consider the following nuclear reaction, in which the molar mass of each species is indicated to four decimal places:. Answer: energy
[EX A]: Nuclear changes occur with a simultaneous release of what, and a slight drop in mass?

[EX Q]: Passage: Electric current occurs whenever there is a difference in electric potential energy, or voltage. Voltage is measured in volts (V). Answer: volts
[EX A]:
What is the unit used to measure voltage?