WAEC Chemistry Past Questions & Answers - Page 47

231.

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 )

232.

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

233.

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.

234.

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

235.

A solid with higher melting and boiling points is likely to be?

A.

Covalent compound

B.

A Dative compound

C.

An Electrovalent compound

D.

A Non-metal

Correct answer is C

Ionic Compounds / Electrovalent compounds Have A High Melting Point and High Boiling Point.