Two tanks (tank a and tank b) of gas are connected by a closed valve. tank a is 5 liters and contains o2 gas at a pressure of 24 atm. tank b is 3 liters and contains n2 gas at a pressure of 32 atm. both tanks are held at the same temperature. the valve between the two tanks is opened and the gases are allowed to mix. after the gases have had time to mix, what is the partial pressure of the oxygen gas?

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.