Potassium (K), atomic number 19, will most likely react with which of the following elements? odium, (Na), because it is in the same column
odium, (Na), because it is in the same column

Calcium (Ca), because it is in the same row.
Calcium (Ca), because it is in the same row.

Chlorine (Cl), because it is a nonmetal
Chlorine (Cl), because it is a nonmetal

Argon (Ar), because it is a noble gas

the results is a decrease in air temperature with an increase of altitude.

explanation:

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.

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.