What happens to the motion of molecules in a substance is cooled?

The motion becomes smaller. Lets tale the example of water. At gaseous state, the particles moves rapidly in all directions. As it is cooled, it becomes liquid and the motion becomes smaller because the particles are now closer to each other as the attraction forces becomes stronger. As it is cooled further, it becomes solid. At solid state, the particles now vibrate in fixed position. Apply this concept to motion of molecules in a substance.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer