Boyle's law applied on mixture of gases
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.