You are the captain of a ship, and you just hit an iceberg. Water is rushing into the ship and it is quickly sinking. A total of 10 people are on the ship and all of them are in grave danger! Hungry sharks are everwhere! The good news is that you have a lifeboat onboard. The bad news is that it only has room for 5 people. You don't know any of the people very well (only the information provided), and you don't have time to interview them before hopping onto the lifeboat. So, you do you keep, and why (and you do NOT have to keep yourself)?

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. 

And a) oxygen i believe