WAEC Chemistry Past Questions & Answers - Page 78

386.

The gas given off when ethanol reacts with sodium is

A.

Carbon(IV)oxide

B.

Hydrogen

C.

Methane

D.

Oxygen

Correct answer is B

No explanation has been provided for this answer.

387.

The following transition metal ions would be coloured in aqueous solution except________?

A.

Cr3+

B.

Fe3+

C.

Mn3+

D.

Sc3+

Correct answer is D

No explanation has been provided for this answer.

388.

Which of the following pairs of compounds belongs to the same homologous series?

A.

C3H8 and C3H6

B.

C4H10 and C5H10

C.

C2H4 and C4H10

D.

C2H6 and C4H10

Correct answer is D

both ethane and butane are in the same homologous series.( alkanes)

389.

Which of the following pairs of elements forms amphoteric oxides?

A.

Be and Mg

B.

Na and K

C.

B and Al

D.

Si and Pb

Correct answer is D

Metal oxides which react with both acids as well as bases to produce salts and water are known as amphoteric oxides.

Many metals (such as zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides.

390.

A metallic ion Z2+ with an inert gas structure contains 18 electrons. How many protons are contained in this ion?

A.

20

B.

18

C.

16

D.

2

Correct answer is A

No explanation has been provided for this answer.