JAMB Chemistry Past Questions & Answers - Page 308

1,536.

The solubility of copper (II) tetraoxosulphate (Iv) is 75g in 100g of water at 100°C and 25g in 100g of water at 30°C. What mass of the salt would crystallize, if 50g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C ?

A.

57.5

B.

42.2

C.

28.6

D.

14.3

Correct answer is D

solute + solvent = solution

at 100oC; 75g + 100g = 175g

at30oC; \(\frac{25g}{50g}\) + 100g = 125g

From 100oC - 30oC; 175g CuSO4 ppt 50g

From 100oC - 30oC; 50g CuSO4 ppt \(\frac{50 \times 50}{175}\) = 14.3

1,537.

Which of the following ions is a pollutant in drinking water even in trace amounts?

A.

Ca2+

B.

Hg2+

C.

Mg2+

D.

Fe2+

Correct answer is B

No explanation has been provided for this answer.

1,539.

Which of the following is arranged in order of increasing electronegativity?

A.

Chlorine, aluminium, magnesium, phosphorus, sodium

B.

sodium, magnesium, aluminium, phosphorus, chlorine

C.

Chlorine, phosphorus, phosphorous, aluminium, magnesium, sodium

D.

Sodium, chlorine, phosphorus, magnesium, aluminium

Correct answer is B

No explanation has been provided for this answer.

1,540.

Which of the following represents the type of bonding present in ammonium chloride molecule?

A.

Ionic only

B.

Covalent only

C.

Ionic and dative covalent

D.

Dative covalent only

Correct answer is C

No explanation has been provided for this answer.