Atank containing both hf and hbr gases developed a leak. the ratio of the rate of effusion of hf to the rate of effusion of hbr is

2.01

Explanation:

The effusion is the passage of the molecules by a small hole by a difference of pressure. By Graham's Law, the rate of the effusion is inversely proportional to the square of the molar mass of the compound. Thus,

rateHF/rateHBr = √MHBr /√MHF

MHBr = 81 g/mol

MHF = 20 g/mol

rateHF/rateHBr = √81/√20

rateHF/rateHBr = 2.01

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.