Boyle's law applied on mixture of gases Q1. If $\pu{1.00L}$ of oxygen gas at $\pu{1.00 bar}$ pressure is combined with $\pu{1.00L}$ of nitrogen gas at $\pu{1.00 bar}$ pressure in a $\pu{2.00L}$ vessel, what is the total pressure in the vessel?

a) $\pu{0.50 bar}$
b) $\pu{1.00 bar}$
c) $\pu{2.00 bar}$
d) $\pu{4.00 bar}$

Q1. If $\pu{1.00L}$ of oxygen gas at $\pu{1.00 bar}$ pressure is combined with $\pu{1.00L}$ of nitrogen gas at $\pu{1.00 bar}$ pressure in a $\pu{1.00L}$ vessel, what is the total pressure in the vessel?

a) $\pu{0.50 bar}$
b) $\pu{1.00 bar}$
c) $\pu{2.00 bar}$
d) $\pu{4.00 bar}$

My thought process:

I know that Boyle's law states that the volume of a fixed quantity of gas at constant temperature is inversely proportional to the pressure, so in these cases it is safe to assume that Boyle's law can be used. For Q1, would the answer be simply 2.00 bars (c)? Instinct tells me it is, but I can't seem to explain why. For Q2, I'd think the answer is 4.00 bar (d) because the volume is halved, so the pressure should be doubled? Again, I'm not too sure though. Any help would be much appreciated.
you have both answers wrong.

(1) b - The volume of oxygen and nitrogen are both 1 liter at 1 bar, but they are put into a 2 liter container. So the pressure stays the same. 

(2) c - The volume of oxygen and nitrogen are both 1 liter at 1 bar, but they are put into a 1 liter container. Since the volume is halved the pressure must double.