Answer
At equilibrium both the left and right bulbs will have 5 blue and 5 red gas particles for a total of 10 gas particles in each bulb.
Work Step by Step
Count the number of blue gas molecules in the left bulb, and count the number of red gas molecules in the right bulb initially with the closed stopcock.
Left Bulb: 10 blue gas molecules
Right Bulb: 10 red gas molecules
At equilibrium we assume each bulb, both left and right, to have an equal number of both blue and red gas molecules on each side.
