Which of the following is true about rocks?
a. rocks are composed of only one mineral.
b. rocks do not contain any nonmineral matter.
c. coal is not considered a true rock.
d. most rocks are a mixture of minerals.

If steel is more dense that lake water, why can a boat float

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

The average density of the planet uranus is 1.27 103 kg/m3. the ratio of the mass of neptune to that of uranus is 1.19. the ratio of the radius of neptune to that of uranus is 0.969. find the average density of neptune.