Hope u do well :) ik this maybe hard but you’ll get through it , the answer is D !
To determine whether the amount of H2 in the lab is dangerous, we first need to know how much hydrogen gas is present in the room in units of percent by volume. For this particular problem, we cannot exactly determine since we do not know the total volume of the room. Hope this answers the question.
Solve these problems like weighted averages:
The first one:
Multiply the masses (isotope numbers) by the decimal form of the percentage. Add them
0.076 (6) + 0.924 (7) = 6.924
The second one:
0.2 (10) + 0.8 (11) = 10.8
If you think about it, these answers make sense. 6.924 is much closer to 7 than to 6 (since there's a lot more lithium-7 than there is lithium-6). 10.8 is closer to 11 than to 10.
True some explanations are not always based on empirical evidence
