The answer is b. Food chains are extremely fragile. In many occasions, the health of a species will depend on the survival of the species right under. At the end, we realize that the chain is quite fragile because everyone depends on each other, but not every species are strong enough to survive the change in their environment.
Convert amount of molecules into moles using Avogadro’s number
9.40 x 10^25 molecules H2 x 1 mole / 6.02 x 10^23 molecules
= 156 moles H2
Convert moles of H2 into grams using H2’s molar mass (1.01 x 2 = 2.02)
156 mol H2 x 2.02 g / 1 mol
= 315 g H2
