JAMB Chemistry Past Questions & Answers - Page 149

741.

The mass of an atom is determined by

A.

its ionization potential

B.

its electrochemical potential

C.

the number of protons and electrons

D.

the number of neutrons and protons

E.

the number of neutrons and electrons

Correct answer is D

No explanation has been provided for this answer.

742.

Which of the following solutions will give a white precipitate with barium chloride solution and a green flame test?

A.

Na2SO4

B.

CuSO4

C.

CaSO4

D.

CaCI2

E.

(NH4)2SO4

Correct answer is B

No explanation has been provided for this answer.

743.

A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is

A.

O2

B.

NO

C.

SO2

D.

NH3

E.

CO2

Correct answer is C

No explanation has been provided for this answer.

744.

The cracking process is very important in the petroleum industry because it.

A.

gives purer products

B.

yields more lubricants

C.

yields more engine fuels

D.

yields more asphalt

E.

yields more candle wax

Correct answer is C

No explanation has been provided for this answer.

745.

3. 06 g of a sample of potassium trioxochlorate (V) (KCIO\(_3\)) was required to make a saturated solution with 10cm\(^3\) of water at 25°C. The solubility of the salt at 25°C is [K =39, Cl = 35.5, O = 16]

A.

5.0 moles dm3

B.

3.0 moles dm3

C.

2.5 moles dm3

D.

1.0 molesv

E.

0.5 moles dm3

Correct answer is C

Molar mass of KCIO\(_3\) = 122.5 g/mol

3.06g = 10
xg = 1000

\(frac{3.06 * 1000}{10}\)

= 306g
Molar conc = \(frac{Mass conc}{Molar mass}\)
Molar conc = \(frac{306}{122.5}\)

= 2.497mol/dm\(^3\)