Which pair of elements would you expect to exhibit the greatest similarity in their physical and chemical properties? o, s si, p?

I believe the appropriate pair is O and S, Periodic table represents arrangements of elements ordered by their atomic number,physical and chemical properties. Both sulfur and oxygen are in the same group of the periodic table (group 6), they have a valency of 2, This means they have a greater similarity in chemical and physical properties.

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.