Voltaic cells produce a positive overall cell potential. what does this indicate?

Explanation:

Voltaic cell is a cell in which a chemical reaction occurs that leads to generation of electricity.

To calculate cell potential of a voltaic cell, the formula is as follows.

                                    = +ve

Also, a positive cell potential indicates that a reaction is spontaneous as follows.

                      = - nF

                              = (-ve)(+ve)

                              = -ve

Therefore, value of comes out to be -ve. Therefore, it shows that when voltaic cells produce a positive overall cell potential then the reaction is spontaneous.

i believe the answer is a.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.