While at the dentist’s office, Marion noticed the x-ray images of her teeth looked very different than a photograph image of her teeth. She recalled x-ray images are produced from x-rays and photograph images are produced from visible light waves. What can be infered about the energy difference between x-rays and visible light waves?
A. X-rays have higher energy than visible light waves.
B. Visible light waves have higher energy than x-rays.
C. X-rays and visible light waves have the same energy.
D. Visible light waves and x-rays can have varying amounts of energy.

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. 

16- counting by fours

Both models are effective because they show the valence electrons, and these valence electrons indicate the reactivity of an element.