The 2nd question (the answer is c) but i don't know why so can someone solve this for me ?

The formula for surface area of a sphere is A=4*PI*r^2

Using that formula and the known surface are we can find the radius. We can then use that to find the volume.

500 = 4*PI*r^2

Divide both sides by 4:
500/4 = PI *r^2
125 = PI *r^2

Divide both sides by PI

125/PI = r^2
39.79 = r^2
r = SQRT(39.79)
r = 6.3 cm

Now we can find volume using V=4/3*PI*r^3

V = 4/3 *PI *6.3^3

V= 1051.3

The answer is C