JAMB Chemistry Past Questions & Answers - Page 6

26.

Which type of salt is found in antacid medications and is used to relieve heartburn and indigestion?

A.

Aluminum chloride

B.

Magnesium chloride

C.

Sodium chloride

D.

Calcium chloride

Correct answer is B

Magnesium chloride is used in antacid medications to relieve heartburn and indigestion. It helps neutralize excess stomach acid.

27.

When anhydrous cobalt chloride paper is exposed to water, what color change is observed?

A.

From pink to blue

B.

From white to blue

C.

From blue to white

D.

From blue to pink

Correct answer is D

nhydrous cobalt chloride paper is blue in the absence of water. However, when it comes into contact with water, it undergoes a color change to pink due to the formation of hydrated cobalt chloride.

28.

What is the valency of an element with the electronic configuration 2, 8, 7?

A.

7

B.

1

C.

2

D.

3

Correct answer is B

The valency of an element is determined by the number of electrons it gains or loses to achieve a stable electron configuration. For an element with the electronic configuration 2, 8, 7, the outermost shell (valence shell) has 7 electrons. To achieve stability, it needs 1 more electron to fill the outermost shell, so its valency is 1.

29.

Which of the following methods is commonly used to remove suspended impurities from water?

A.

Fluoridation

B.

Chlorination

C.

Filtration

D.

Distillation

Correct answer is C

Filtration is commonly used to remove suspended impurities, such as dirt, sand, and other particles, from water. In this process, water is passed through a filter medium that traps the solid impurities while allowing the clean water to pass through.

30.

Which transition metal is known for its multiple colorful oxidation states and compounds used in pigments and paints?

A.

Silver (Ag)

B.

Copper (Cu)

C.

Gold (Au)

D.

Zinc (Zn)

Correct answer is B

Copper is known for its multiple oxidation states, including +1 and +2, and its compounds are used in pigments and paints to create various colors, such as blues and greens.