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.

3,701.

1.0 dm3 of distilled water was used to wash 2.0g of a precipitate of AgCl. If the solubility product of AgCl is 2.0 * 10-10mol2dm-6, what quantity of silver was lost in the process?

A.

2.029 * 10-3mol dm-3

B.

1.414 * 10-3mol dm-3

C.

2.029 * 10-5mol dm-3

D.

1.414 * 10-5mol dm-3

Correct answer is D

In order to calculate this, it suffices to calculate the solubility of Ag, so as to know the amount lost.

\(K_{sp} = [Ag^{+}][Cl^{-}]\)

Let the solubilty of Ag and Cl = d

\(2 \times 10^{-10} = d \times d= d^{2}\)

\(d = \sqrt{2\times10^{-10}}\)

= \(1.414 \times 10^{-5}moldm^{-3}\)

3,702.

The air pollutant unknown in nature is

A.

NO

B.

CO

C.

HCHO

D.

DDT

Correct answer is C

Formaldehyde (HCHO) is the most important carcinogen in outdoor air among the 187 hazardous air pollutants (HAPs) identified by the U.S. Environmental Protection Agency (EPA)

3,703.

Water molecule can be ligands especially when they are bonded to

A.

alkaline earth metals

B.

alkali metals

C.

transition metals

D.

group VII elements

Correct answer is C

No explanation has been provided for this answer.

3,704.

A side effect of soft water is that

A.

it gives offensive taste

B.

excess calcium is precipitated

C.

it attcaks lead contained in pipes

D.

it encourages the growth of bacteria

Correct answer is C

No explanation has been provided for this answer.

3,705.

The noble gas, argon,is used for

A.

electric arc welding

B.

welding brass

C.

underwater welding

D.

steel welding

Correct answer is A

No explanation has been provided for this answer.