If you are given 7.34moles of a gas at 540K and a pressure of 2.3atm, what is the volume of the gas?

140 L (141.409 without rounding)

Explanation:

Assuming ideal behavior (so that we can use the ideal gas law), we can plug into the equation PV=nRT.  P=2.3 atm, n=7.34 mol, and T=540 K.  (If converting from Celsius to Kelvin, add 273.15.) For R, we'll use 0.082057 L*atm/(mol*K) so that the units cancel out.  2.3 atm*V=7.34 mol*.082057 Latm/(molK)*540 K.  Divide both sides by 2.3 to get the Volume in liters.  That will give you a volume of 140 L (with sig figs.  If you don't round it, you'd get 141.409 L).

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.