What is common about the elements of a period? select all that apply. they have the same number of electron energy levels. they have similar chemical characteristics. they have similar physical characteristics. they transition from a metal to noble gas.

The correct statements are they have the same number of electron energy levels and they transition from a metal to noble gas.

Explanation:

Elements are arranged in 7 periods and 18 groups in a periodic table.

Elements that are arranged in same group have same number of valence electrons and hence show similar chemical properties.

Elements that are arranged in same period have same number of energy levels. In a periods, first metals come, then non-metals and a period ends with a noble gas always.

Hence, the correct statements are they have the same number of electron energy levels and they transition from a metal to noble gas.

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.