Ametal sphere has a mass of 39.0g and a volume of 10.0cm is the sphere made of pure aluminum

Note that the density of pure aluminum is  2.7 g/cm³ (from tables).

Given:
m = 39.0 g, the mass of the metal
V = 10.0 cm³, the density of the metal

By definition, the density of the metal is
density = mass/volume
             = (39.0 g)/(10.0 cm³)
             = 3.9 g/cm³

The calculated density is not equal to 2.7 g/cm³, therefore the metal sphere is not made of pure aluminum.

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

It decreases by 4 is your answer mark brainliest