To reduce the energy of liquid molecules, the liquid could be placed in a cooler environment to change the liquid to a solid. true false

True

Explanation:

Solid state : It is a state in which the particles are closely packed and does not have any space between them. They have least kinetic energy due to restricted movement. This state has a definite shape and volume.

Liquid state : It is a state in which the particles are present in random and irregular pattern. The particles are closely arranged but they can move from one place to another and thus have higher kinetic energy as compared to solids. This state has a definite volume but does not have a fixed shape.

Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is determined by the equation:

K= kinetic energy

R= gas constant

T= temperature  

From above, it is visible that kinetic energy is directly related to the temperature of the system. So, when liquid is placed in a cooler environment to change the liquid to a solid , the energy decreases.

The NH3 + with a PKa = 9.9

Explanation:

The Pka is a mathematical expression to express the dissociation grade of a substance in a solution, that means with a substance with a pKa small is a strong acid, and in this case since the solution pH is 8, that mean that the substance with high pKa ( lower acid strength)  will predominate in a pH of 8.