Magnesium carbonate and hydrochloric acid react to produce salt, water and carbon dioxide.
MgCO3 + 2 HCl → MgCl2 + H2O + CO2
+
What is the volume of CO2 produced when 21 g of magnesium carbonate reacts
completely with excess hydrochloric acid?

the ratio of the conjugate base to the acid required to attain the desired ph.

the right answer is c i just did the question.

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.