When we say that the weight of an object is Mg, and that g = 9.8 N/kg, what assumptions are we making?

Question

Which of the below?

-The distribution of mass in the earth is spherically symmetric.
-The density of the earth is the same everywhere.
-The earth's interior is solid everywhere.
-The orbit of the earth is circular and not elliptical.
-We neglect the effect of astronomical bodies other than the earth.
-The object is at the earth's surface.
-Two significant figures are sufficient.
-Newton's law of gravitation holds.

Answer 1

-The distribution of mass in the earth is spherically symmetric.
Yes, if all the mass were under Paris, g would be very high there.

-The density of the earth is the same everywhere.
No, all the mass could be at the center

-The earth's interior is solid everywhere.
No, again all the mass could be at center

-The orbit of the earth is circular and not elliptical.
Not relevant

-We neglect the effect of astronomical bodies other than the earth.
Yes

-The object is at the earth's surface.
Yes

-Two significant figures are sufficient.
Yes

-Newton's law of gravitation holds.
Yes