Milk is considered a colloid select one: it is a homogeneous mixture. it is a mixture of two or more substances that appears to be a single substance, even under a microscope. it is a pure substance that does not contain more than one type of chemical. it contains small clumps of protein that do not settle over time.

 It contains small clumps of protein that do not settle over time.

Explanation: Milk appears to be a homogeneous mixture but actually is a heterogeneous mixture which consists of fat particles as dispersed phase suspended in the dispersion medium which is water.The dispersed phase is visible when placed under microscope.

They have particle size intermediate between true solutions and suspensions.

True solutions are homogeneous mixtures in which dispersed particles are evenly distributed. Suspensions have large dispersed particles which settle when left undisturbed.

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.