Which Period 3 element would you expect to have the highest electrical and thermal conductivity?
A. Chlorine (CI)
B. Phosphorus (P)
C. Sulfur (S)
D. Sodium (Na)

The correct option is D

Explanation:

Generally, thermal and electrical conductivity is affected by valence electrons in an atom. These valence electrons carry electric charges (or conduct heat as the case may be) throughout the atom. The fewer the valence electrons, the higher its conductivity - this is as a result of free movement within the atom. The higher the valence electrons, the lesser its conductivity and when the outermost electrons have completely filled the outermost shell, the atom would be an insulator as there won't be carriers of electric charges.

Hence, from the above, sodium would be expected to have the highest electrical and  thermal conductivity because it has just one electron in it's outermost shell

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.