NECO Chemistry Past Questions & Answers - Page 30

146.

The Atomic theory model which explains that electrons in an atom revolve round quantized energy levels is attributed to

A.

Becquerel

B.

Bohr

C.

de Broglie.

D.

Rutherford

E.

Thompson

Correct answer is B

No explanation has been provided for this answer.

147.

White is NOT a property of metals?

A.

ductile

B.

malleable

C.

conduct heat and electricity

D.

have many oxidation states

E.

high melting points anti boiling points

Correct answer is D

No explanation has been provided for this answer.

149.

The high boiling point of hydrogen fluoride can be explained in terms of

A.

covalent bonds.

B.

dative bonds.

C.

dipole-dipole bonds.

D.

electrovalent (ionic) bonds

E.

hydrogen bonds.

Correct answer is E

No explanation has been provided for this answer.

150.

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

A.

1

B.

-2

C.

3

D.

4

E.

5

Correct answer is E

The oxidation number of O  is 2-

Therefore, let the oxidation number of X be a

a + (-2 x 4) = -3

a - 8 = -3

a = -3+8

a = 5