JAMB Chemistry Past Questions & Answers - Page 163

811.

Water is said to be temporarily hard when it contains

A.

Ca (HCO3)2 and Mg (HCO3)2 salts

B.

Ca (HCO3)2 and CaCO3 SALTS

C.

Mg(HCO3)2 and CaSO4 salts

D.

CaSO4 and Ca(HCO3)2 salts

Correct answer is A

Temporary hardness is caused by the presence of dissolved calcium hydrogentrioxocarbonate(IV)  and magnesium hydrogentrioxocarbonate(IV) which decomposes on heating to form calcium trioxocarbonate(IV) and magnesium trioxocarbonate(IV) respectively.

812.

A silicon -containing ore has 92% 28Si, 5% 29Si and 3% 30Si. Calculate the relative atomic mass of the silicon.

A.

14.00

B.

29.00

C.

28.11

D.

28.00

Correct answer is C

(\(\frac{92}{100}\) x 28) + (\(\frac{5}{100}\) x 29) + (\(\frac{3}{100}\) x 30) = 28.11

813.

The radio active radiation used in studying the arrangement of particles in giant organic molecules is

A.

\(\gamma\)- rays

B.

\(\alpha\)- particles

C.

X-rays

D.

\(\beta\) - particles

Correct answer is C

No explanation has been provided for this answer.

814.

How many protons, neutrons and electrons respectively are present in the element 60/27 Co?

A.

27, 33 and 33

B.

33, 27 and 27

C.

27, 33, and 27

D.

60, 33 and 60

Correct answer is C

No explanation has been provided for this answer.

815.

If the difference in electronegativity of elements P and Q is 3.0. The bond that will be formed between them is

A.

metallic

B.

covalent

C.

co-ordinate

D.

ionic

Correct answer is D

No explanation has been provided for this answer.