5.2 moles of nitrogen gas are contained in a 3.4 L container. If pressure is kept constant what is the final molar amount of gas present in the container if gas is added until the
volume has decreased to 2000 mL?

Noble gases is far right

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. 

C. control over the business

Depends on the speed of the car.