Answer:
B
Explanation:
Recall the law of effusion:

Because 5 mol of oxygen was effused in 10 seconds, the rate is 0.5 mol/s.
Let the rate of oxygen be <em>r</em>₁ and the rate of hydrogen be <em>r</em>₂.
The molecular weight of oxygen gas is 32.00 g/mol and the molecular weight of hydrogen gas is 2.02 g/mol.
Substitute and solve for <em>r</em>₂:

Because there are 5 moles of hydrogen gas:

In conclusion, it will take about 2.5 seconds for the hydrogen gas to effuse.
Check: Because hydrogen gas is lighter than oxygen gas, we expect that hydrogen gas will effuse quicker than oxygen gas.
First convert celcius to Kelvin.
20 + 273 = 293K
31 + 273 = 304K
Now we can set up an equation based on the information we have.
V1 = 5
P1 = 365
T1 = 293
V2 = 5
P1 = x
T2 = 304
The equation be: 
Now just solve.
1825/293 = 5x/304
Cross multiply.
554800 = 1465x
Divide both sides by 1465
x = 378.7030717 which can then be rounded to 378.7 mmHg
<span>Fluorine ONLY form\s an ion with a -1 charge. The other three are metals, and metals for positively charged ions.</span>