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.

396.

Calcium and magnesium belong to the group of the periodic table because both?

A.

are metals

B.

form cations

C.

form colourless salts

D.

have same number of valence electrons

Correct answer is D

No explanation has been provided for this answer.

397.

If 6.5g of magnesium ribbon reacts completely with Hydrochloric acid, how many grams of hydrogen gas would be liberated?

Mg(s) + 2 HCl(aq) --> MgCl 2(aq) + H 2(g)

[ H = 1.0, Mg = 24.0 ]

A.

0.54g

B.

0.70g

C.

1.08g

D.

1.40g

Correct answer is A

  24g of Mg will liberate 2g of H

: 6.5g of Mg will liberate Xg of H

= ( 6.5 X 2 ) / 24

= 0.5416g of Hygrogen ( H )

398.

The bleaching action of chlorine is through the process?

A.

Hydration

B.

Hydrolysis

C.

Reduction

D.

Oxidation

Correct answer is D

The bleaching action lof chlorinr is due to its ability to react with water to form oxochlorate(i)acid

399.

which of the following elements has the highest ionization energy?

A.

Calcium

B.

Chlorine

C.

Flourine

D.

Magnesium

Correct answer is C

The ionisation energy is the minimum energy required to remove the most loosely bound electron of an isolated gaseous atom, positive ion, or molecule.

Fluorine has the highest ionization energy when assessed through the trend on the periodic table.

400.

Which of the following metals reacts slowly with cold water?

A.

Iron

B.

Silver

C.

Calcium

D.

Pottassium

Correct answer is C

Calcium reacts very slowly with cold water