JAMB Chemistry Past Questions & Answers - Page 36

176.

The chlorinated alkane often used industrially to remove grease is?

A.

Tetrachloromethane

B.

Chloromethane

C.

Trichloromethane

D.

Dichloromethane

Correct answer is A

Tetrachloromethane ( carbon tetrachloride) is an effective solvent within the chemical industry and is used to clean machinery and electrical equipment. 

I.e as a solvent for oils, fats, lacquers, varnishes, rubber waxes, and resins, and as a grain fumigant.

177.

The substance often used for vulcanization of rubber is?

A.

Chlorine

B.

Hydrogen peroxide

C.

Sulphur

D.

Tetraoxosulphate(vi) acid

Correct answer is C

One of the several uses of sulfur is for the vulcanization of rubber.

178.

An organic compound that does not undergo a reaction with both hydrogen cyanide and hydroxylamine can be?

A.

Alkene

B.

Alkanal

C.

Alkanone

D.

Alkanoic Acid

Correct answer is A

Alkanone & alkanal react with HCN to form compounds known as cyanohyderins. They also react with hydroxylamine to form oximes.

179.

Which of the following types of bonding does not involve the formation of new substances?

A.

Metallic

B.

Covalent

C.

Co-ordinate

D.

Electrovalent

Correct answer is A

Metallic bond does not involve the formation of a new substance. It is responsible for several characteristic properties of metals such as their shiny lustre, their malleability, and their conductivities for heat and electricity

180.

What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?

A.

24,125 C

B.

48,250 C

C.

72,375 C

D.

96,500 C

Correct answer is B

4OH ⇒ 2H\(_2\)O + O\(_2\) + 4e-

From the equation:

1 mole of Oxygen requires 4e 

i.e 1 mole of Oxygen requires 4F,

where 1F = 96,500 C

[ 4 X 96,500 X 0.125 ] ÷ 1

= 48,250 C