Chemistry questions and answers

Chemistry Questions and Answers

Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.

1,286.

The oxidation number of Fe in [Fe(CN)\(_6\)]\(^{3-}\) is

A.

+3

B.

+2

C.

-2

D.

-3

Correct answer is A

Let the oxidation number of Fe in the compound [Fe(CN)\(_6\)]\(^{3-}\) be x.

x + 6(-1) = -3

x - 6 = -3;

x = -3 + 6

x = +3

1,287.

Which of the following devices function on redox reaction? l. Dry cell ll. Car battery III. Electric generator

A.

l and lll only

B.

ll and lll only

C.

l and ll only

D.

l, ll and lll

Correct answer is C

No explanation has been provided for this answer.

1,288.

Consider the reaction represented by the following equation: CuO\(_{(s)}\) + H\(_2\)SO\(_{4(aq)}\) → CuSO\(_{4(aq)}\) + H\(_2\)O\(_{(l)}\). Which of the following factors will not affect the rate of the reaction?

A.

Particle size of CuO(s)

B.

Concentration of H2SO4(aq)

C.

Temperature of the reacting mixture

D.

Pressure of reaction system

Correct answer is D

The reaction rate between a solid and liquid will not be affected by pressure. Pressure majorly affects the reaction rate for gases.

1,289.

A spot of oil paint on a shirt can best be removed using?

A.

brine

B.

detergent

C.

kerosine

D.

warm water

Correct answer is C

To remove oil paints, the use of chemicals is usually required, including turpentine, acetone, kerosene, and various paint thinners. 

1,290.

The hydrolysis of NH\(_4\)CI gives

A.

an acidic solution

B.

an alkaline solution

C.

a buffer solution

D.

a neutral solution

Correct answer is A

When you dissolve ammonium chloride crystals in water (H\(_2\)O), the ammonium chloride compound decomposes into its component ions: NH\(_4 ^+\) and Cl\(^-\). The reaction of these ions with water gives an acidic solution.