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JAMB Chemistry Past Questions & Answers - Page 142

706.

In the preparation of some pure crystals of Cu (NO3)2 starting with CuO, a student gave the following statements as steps he employed. Which of these shows a flaw in his report ?

A.

some CuO was reacted with excess dilute H2SO4

B.

the solution was concentrated

C.

when the concentrate was cooled, crystals formed were removed by filtration

D.

the crystals were washed with very little cold water

E.

the crystals were then allowed to dry

Correct answer is A

No explanation has been provided for this answer.

707.

Some metals are extracted from their ores after some preliminary treatments by electrolysis (L), some of both processes (TL). Which set-up in the following for the extraction of ion, copper and aluminium is correct?

A.

lron (L), copper (L) aluminium (T)

B.

lron (T) copper (L) aluminium (T)

C.

lron (TL) copper (TL) aluminium (TL)

D.

Iron (L) copper (T) aluminium (T)

E.

lron (T) copper (L), aluminium (TL)

Correct answer is E

No explanation has been provided for this answer.

708.

Which of the following pair of gases will NOT react further with oxygen at a temperature between 30oC AND 400oC

A.

SO2 and NH3

B.

CO2 and H2

C.

NO2 and SO3

D.

SO3 and NO

E.

CO and H2

Correct answer is C

No explanation has been provided for this answer.

709.

Which volume of 0.5 M H 2SO4 will exactly neutralize 20 cm 3 of 0.1 M NaOH solution?

A.

2.0 cm 3

B.

5.0 cm 3

C.

6.8 cm 3

D.

8.3 cm 3

E.

10.4 cm 3

Correct answer is A

CAVACbVb=12

frac0.5×VA0.1×20=12

V_A = \frac{0.1 \times 20}{2 \times 0.5} = \frac{1.0}{0.5)

= 2cm2

710.

Stainless steel is an alloy of

A.

carbon, iron and lead

B.

carbon, iron and chromium

C.

carbon, iron and copper

D.

carbon, iron and silver

E.

carbon and iron only

Correct answer is B

No explanation has been provided for this answer.