JAMB Past Questions and Answers - Page 1588

7,936.

A colourless organic compound X was burnt in excess air to give two colourless and odourless gases, Y and Z, as products. X does not decolorize blue bromine vapour, Y turns lime milky while Z gives a blue colour with copper (ll) tetraoxosulphate (IV).
Compound X is?

A.

an alkene

B.

an alkane

C.

an alkyne

D.

tetrachloromethane

E.

dichloromethane

Correct answer is B

Burning the alkane in the presence of sufficient air or oxygen; it produces carbon dioxide, water, and a huge amount of heat as a product.

If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.

Anhydrous CuSO4 is used to test the presence of water in any liquid because it changes its colour from white to blue in the presence of water.

7,937.

Which of the following substances is the most abundant in the universe?

A.

Carbon

B.

Air

C.

Water

D.

Oxygen

E.

Hydrogen

Correct answer is E

Element Abundance
Hydrogen 40,000
Helium 3,100
Oxygen 22
Neon 8.6
Nitrogen 6.6
Carbon 3.5
Silicon 1
Magnesium 0.91
Iron 0.6
Sulfur 0.38

7,938.

Solid sodium hydroxide on exposure to air absorbs a gas and ultimately gives another alkaline substance with the molecular formula?

A.

NaOH.H2O

B.

NaOH.N2

C.

Na2CO3O

D.

NaHCO3

E.

NaNO3O

Correct answer is C

No explanation has been provided for this answer.

7,939.

An organic compound decolourized acidified KMnO4 solution but failed to react with ammoniacal silver nitrate solution. The organic compound is likely to be?

A.

a carbonxylic acid

B.

an alkane

C.

an alkene

D.

an alkyne

E.

an akanone

Correct answer is C

No explanation has been provided for this answer.

7,940.

Tetraoxosulphate (IV) ions are finally tested using?

A.

acidified silver nitrate

B.

acidified barium chloride

C.

ime-water

D.

dilute hydrochloric acid

E.

acidified lead nitrate

Correct answer is B

No explanation has been provided for this answer.