Moles of Oxygen they took in : C. 2.42
<h3>Further explanation</h3>
The gas equation can be written

where
P = pressure, atm
V = volume, liter
n = number of moles
R = gas constant = 0.08205 l.atm / mol K
T = temperature, Kelvin
P=1000 kPa
V = 6 L
T = 298 K
moles of Oxygen :

there are no choices of statements
Answer:
A
Explanation:
You want one whole number to the left of the decimal. Depending on how many times u have to move the decimal over (in this case 7 times) determines the number you put after 10. And its -7 because to get it back to its original position you have to move left, which is a negative direction.
Molar mass HBr = 80.91 g/mol
number of moles:
mass of solute / molar mass
52 / 80.91 => 0.642 mols
Volume = 0.25 L
M = n / V
M = 0.642 / 0.25
M = 2.568 mol/L
hope this helps!