A sample of oxygen (O2) occupies 452 mL at a pressure of 681 torr and a temperature of 26°C. What pressure will the oxygen exert if: a) the volume is decreased to 419 mL while temperature is held constant?
b) the temperature is decreased to 11°C while the volume is held constant?
c) the temperature is decreased to 11°C and the volume is decreased to 419 mL?

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. 

Sorry i dont understand the question can you rephase it?