JAMB Past Questions and Answers - Page 1540

7,696.

Starch can be converted to ethyl alcohol by

A.

distillation

B.

fermentation

C.

isomerization

D.

cracking

E.

cooking

Correct answer is B

No explanation has been provided for this answer.

7,697.

Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by

A.

dissolving it in water, recrystallizing it and then drying in the oven

B.

passing it through a concentrated aqueous solution of sodium hydroxide

C.

passing it through calcium oxide

D.

passing it through concentrated sulphuric acid

E.

passing it through anhydrous calcium choride

Correct answer is C

No explanation has been provided for this answer.

7,698.

In which of the following reactions is sulphur dioxide acting as an oxidizing agent?

A.

SO 2 + 2HNO3 →H2SO4 + NO2 + Heat

B.

2SO2 + 2H2O + O2→ 2H2SO4

C.

SO2 + 2H2O + CI2→ H2SO4 + 2HCI

D.

SO2 + 2H2S → 3S + 2H2O

E.

SO2 + H2O → H2SO3

Correct answer is D

No explanation has been provided for this answer.

7,699.

An anhydride is?

A.

a compound wich has no water of crystallization

B.

an oxide whose solution in water has a PH greater than 7

C.

an oxide whose solution in water has a PH less than 7

D.

an oxide that has hydrogen atoms

E.

an amphoteric oxide

Correct answer is A

No explanation has been provided for this answer.

7,700.

In the redox reaction\( 2Fe^{2+} + CI_2 → 2Fe^{3+} + 2Cl^-\)

A.

Cl2 is reduced because it has lost electrons

B.

Cl2 is reduced because its oxidation number has decreased

C.

Cl2 is reduced because its molecule is change to two ions

D.

Fe2+ is reduced because it has lost electrons

E.

Fe2+ is reduced because it has gained electrons

Correct answer is B

decrease in oxidation number indicates reduction while an increase in oxidation number indicates oxidation hence chloride gas is reduced because its oxidation number changed from o to -1