Which of these is a chemical property of iron?
a.
it is dense.
b.
it has a melting point.
c.
it is hard to bend.
d.
it becomes rusted.

On mars a rock falls an unknown vertical distance from a resting position and lands in a crater. if it takes the rock 2.5 seconds to fall, how high is the cliff the rock fell from? mars' surface gravity is 3.8 m/s2. a. 9.5 m b. 11.9 m c. 15.2 m d. 23.8 m