The mass of a radioisotope falls from 2g to 0.25g in 3 hours. What is the half-life of this radioisotope?

no but i do not usually comment or use my voice that much when it comes to social media

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.