WAEC Chemistry Past Questions & Answers - Page 29

141.

Dilution factor is the?

A.

amount of distilled water that is added to the concentrated solution to dilute it

B.

Quantity of distilled water added to l dm\(^3\) of the concentrated solution to give the dilute solution

C.

number of times the volume of the concentrated solution is diluted to give the dilute solution

D.

act of diluting the concentrated solution to obtain the dilute solution

Correct answer is C

- Dilution Factor is the factor by which the stock solution is diluted. It may be expressed as the ratio of the volume of the final diluted solution (V2) to the initial volume removed from the stock solution (V1)

- The dilution factor is the total number of unit volumes in which your material will be dissolved.

142.

which of the following quantities is a molar quantity?

A.

Molarity

B.

Molar mass

C.

Mass concentration

D.

Molality

Correct answer is C

No explanation has been provided for this answer.

143.

Which of the following processes is not exhibited by atoms in order to attain more stable electron configuration?

A.

Gaining of electrons

B.

Hybridization of orbitals

C.

Losing electrons

D.

Sharing electron

Correct answer is B

- An atom may give, take, or share electrons with another atom to achieve a full valence shell, the most stable electron configuration.

- Hybrid orbitals are useful in the explanation of molecular geometry and atomic bonding properties and are symmetrically disposed in space.

144.

The atomic number of an atom would be equal to its mass number if it

A.

has a totally filled valence shell

B.

has a high charge to mass ratio

C.

does not contain neutrons

D.

exhibits isotopy

Correct answer is C

- The mass number of an atom is its total number of protons and neutrons

145.

How many electrons does  \({31}_{15}\)P\(^3-\) contain?

A.

12

B.

15

C.

16

D.

18

Correct answer is D

- Phosphorus also has 15 electrons. 

- Here we have P3- which means that this atom has gained 3 electrons. So, P3- has 18 electrons.