JAMB Chemistry Past Questions & Answers - Page 34

166.

The enzyme that converts glucose to ethyl alcohol is?

A.

maltase

B.

zymase

C.

Diatase

D.

Invertase

Correct answer is B

Zymase is an enzyme complex that catalyzes the fermentation of sugar into ethanol and carbon dioxide. It occurs naturally in yeasts.

167.

To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?

A.

Passed over heated copper(ii)oxide

B.

Bubbled through water

C.

Bubbled through conc H\(_2\)SO\(_4\)

D.

Bubbled through conc NAOH

Correct answer is D

carbon(ii)oxide is prepared from carbon(iv)oxide by passing the latter through red-hot carbon and the unchanged CO\(_2\) is removed when the mixture of the gases through conc NAOH.

168.

The most important element on the earth's crust is?

A.

Nitrogen

B.

Hydrogen

C.

Oxygen

D.

Fluorine

Correct answer is C

OxygenO2, is by far the most abundant element in earth's crust at 46.6 percent, nearly half of the mass of the crust.

169.

Aluminum hydroxide is used in the dyeing industry as a?

A.

Dye

B.

Dispersant

C.

Salt

D.

Mordant

Correct answer is D

Aluminum hydroxide is also used as a mordant in dyeing.

170.

An electron can be added to a halogen atom to form a halide ion with?

A.

8 valence electrons

B.

7 valence electrons

C.

2 valence electrons

D.

3 valence electrons

Correct answer is A

halide ion is a halogen atom bearing a negative charge (which is an anion with a charge of -1). The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−).