The occupational safety and health administration has set the limit on the maximum percentage of carbon dioxide (co) in air a worker can breathe at 0.500% by mole. if dry ice (solid co2) is sublimating (becoming a gas) in a room at a rate of 0.500 mol/min, what is the minimum rate that fresh air has to be supplied to the room so that the concentration of co2 in the room doesn't exceed 0.500% by mole? assume the room is well mixed, and the volume of the solid dry ice does not change. number mol air/min what is the percent by mass of oxygen in a gaseous mixture whose molar composition is 0.500% co2 and 99.500% air? the composition of air is 21% mole o2, 79% mole n2, and has an average molar mass of 29.0 g/mol. number % o, by mass

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. 

Maybe you should get some from your teacher and learn more so you can get your grades up and maybe study a bit more