In general, atomic radii a. decrease from left to right in a period and increase down a group. b. increase from left to right in a period and decrease down a group. c. do not change across a period or a group. d. decrease from left to right and decrease down a group. e. increase from left to right in a period and increase down a group

a. decrease from left to right in a period and increase down a group.

Explanation:

Atomic radius of an atom is defined as the total distance from the nucleus to the outermost shell of the atom.

As moving from left to right in a period, more and more electrons get added up in the same shell and the attraction between the last electron and nucleus increases, which results in the shrinkage of size of an atom. Thus, decreasing the atomic radii of the atom on moving towards right of the periodic table.

As moving from top to bottom in a group, there is an addition of shell around the nucleus and the outermost shell gets far away from the nucleus and hence, the distance between the nucleus and outermost shell increases. Thus, increasing the atomic radii of the atom.

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.