How many mols of nitrogen dioxide NO2 is produced when 34 L of oxygen O2 gas reacts. Assume STP. Must attach work for credit. 2NO + O2 → 2NO2

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?

C) the increase in atmospheric pressure pushes the walls of the balloon outward thus making it  is the answer.hope i you.