WAEC Past Questions and Answers - Page 1356

6,776.

The ionization energy is affected by the following factors except

A.

distance of the outermost electron(s) from the nucleus

B.

size of the positive nuclear charge

C.

ability to attract shared electron(s)

D.

screening effect of the inner electron(s)

Correct answer is C

These 3 factors affect the ionization energy:

  • Size of the positive nuclear charge
  • Size of atom (distance of outermost electron from the nucleus)
  • Screening effect of inner shell electrons

6,777.

The oxidation number of X in \(XO_{4}^{3-}\) is

A.

+1

B.

+3

C.

+4

D.

+5

Correct answer is D

\(XO_{4}^{3+}\) = \(X + (-2\times 4) = -3\)

\(X = -3+8 = +5\)

6,778.

Which of the following substances does not have van der Waals' forces?

A.

Copper

B.

Graphite

C.

Neon

D.

Iodine crystals

Correct answer is A

No explanation has been provided for this answer.

6,779.

Which of the following metals has the strongest metallic bond?

A.

\(_{13}Al\)

B.

\(_{19}K\)

C.

\(_{12}Mg\)

D.

\(_{11}Na\)

Correct answer is A

Aluminium has the highest magnitude of charge of +3, hence it will form a stronger metallic bond.

6,780.

Which of the following arrangements indicates the correct decreasing order of ionization energy of period 3 elements?

A.

Na, Al, P, Cl

B.

Cl, P, Al, Na

C.

Na, P, Cl, Al

D.

Al, Na, P, Cl

Correct answer is B

As you move across a period, first ionization energy increases.