Which is a property of every heterogeneous mixture?
a. the mixture is made up of at least two different states.
b. the mixture is made up of something dissolved in a liquid.
c. the composition of the mixture is the same throughout.
d. the characteristics of the mixture change within a sample.

D. The characteristics of the mixture change within a sample.

Explanation: Homogeneous mixture are those mixtures in which dispersed phase is uniformly distributed throughout the dispersion medium and thus the composition is same throughout. There is no physical distinction between the dispersed phase and dispersion medium. Example: Salt in water

Heterogeneous mixture are those mixtures in which dispersed phase is not uniformly distributed throughout the dispersion medium and thus the composition is not same throughout .There is a physical distinction between the dispersed phase and dispersion medium. Example : Oil in water

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.