1) the mass of an object gives gravity, the more massive an object is the more gravity it has on the things around it
2)the earth's mass is so much greater than our own that we feel it's gravity stronger than say the moon which has a smaller mass than the earth
3) mass and how far away you are from the object
4)as mass increases so does gravity (sorry I do not remeber the equation but there are some specific ones for different situations between two massive objects)
5) when distance increases, gravity decreases (again I do not remeber by how much)
Higher because N2 is a gas which will have higher vibrational energy than solid NaCl
Yes absorption takes place the atom absorb photons
