(2) three fewer valence electrons is your answer.
Answer: (3) ppm
Explanation: Concentration is defined as the amount of solute dissolved in a known amount of the solvent or a solution.
Parts per million (ppm) is used to express the concentration when a very small quantity of solute is present in a large quantity of the solution. It is defined as the mass of solute present in one milion 
parts by mass of the solution.
L/s is used to express flow rate.
J/g is used to express energy per unit mass.
kPa is used to express pressure.
The population decreases when the birth rate is less than the death rate.
B. the shape of a molecule determines its properties and interactions
Answer:
B) The pH of a buffer solution does not change significantly when a small amount of acid is added.
C) The pH of a buffer solution is determined by the ratio of the concentration of acid to the concentration of base.
Explanation:
Buffer solution is useful in maintaining the pH of a solution constant . It is made of a weak acid and its salt or a weak base and its salt . Ph of a buffer is given by the following relation .
pH = pKa + log [ A⁻ ] / [ HA ]
A- is a base and HA is a weak acid .
When we add acid , it reacts with A⁻ or base and gets neutralised .
When we add base , it reacts with acid HA and gets neutralised . In this way it maintains the pH of the solution .
