The geometry of small compounds can be predicted using valence shell electron pair repulsion (vsepr) theory, which focuses on the number of bonds and exhibited by each atom.

Sigma, lone pair.

Explanation:

The geometry of small compounds can be predicted using valence shell electron pair repulsion (VSEPR) theory, which focuses on the number of sigma bonds and lone pair exhibited by each atom.

The toughest type of covalent chemical bond is the sigma bonds. These are formed by intersection of atomic orbitals heads on. For diatomic molecules, Sigma bonding is most generally defined using the terminology and methods of symmetry groups.

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.