Nguyên tố hóa học là tập hợp những nguyên tử có cùng

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The answer is b because c don't explain why the moths are on them and it isn't a because as we know only one species of moth does this

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts