Question 30

[yikang_xu4881]

all the answers of #30 are wrong by the order of 1000x.

the calculations mistake kg for g.

[admin]

It's good that you pointed that out but actually, the answers were off by a factor of 100 (5% of 1 kg being 0.05 kg). The question has been updated. Good pick up.

[priya.bork7031]

30) One of the potential problems that NSA engineers foresaw with the lab/rover concept was the possibility that some of the rover's waste products might irretrievably become lost into the atmosphere (due to leaks, for example). If the system burns 1 kg CH4 per day, and 5% of the methane gas cannot be regenerated by the lab due to waste loss, how many mole(s) of H2 will be lost after 1 week of continuous operation?

1. 4.375 x 10-1 moles[x]
2. 2.1 x 10-3 moles[x]
3. 3.6 x 10-2 moles[x]
4. 1.05 moles[x]

INCORRECT:
Your Answer: C
Correct Answer: A
Explanation
1 week = 7 days. The system loses: 0.05 kg CH4 = 0.35 kg per week (350 g). Hydrogen is 4/16 or ¼ of CH4 by weight. Thus, (350 g)(1/4) = 87.5 g H lost or 43.8 mole of H2.

1. According to the explanation shouldn't answer choice A be 4.375 x 10^1 mol then?

[nedaa.asba6809]

The correct answer is 43.8 mole and it is corrected now.

[admin]

Bump.

[james.adam3659]

I thought the explanation for this question was confusing. If you burn 1 kg of Methane per day and the rover is supposed to regenerate that (for the next day, I assume), then when you lose 5% one day, that means that only 95% of the original methane will be there the next day for the rover to use. Then, you would lose 5% of the original 95% and so on and so on...to assume that you start out with 1kg of methane every single day is not exactly right in my opinion. The question did not say that the rover held more than that or say anything about more gas being put in.