3. What is the mass of an object with a density of 1.7 g/cm3 and a volume of 7 cm3? 4. What is the mass of an object with a density of 0.9 g/mL and a volume of 10 mL?

5. What is the volume of a substance with a density of 0.87 g/mL and a mass of 14 g?

6. What is the volume of an object with a density of 2.3 g/mL and a mass of 24 g?

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)

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