JAMB Past Questions and Answers - Page 1494

7,466.

Use the figure above to answer this question. Which of the following is NOT a monomer?

A.

A

B.

B

C.

C

D.

D

Correct answer is A

No explanation has been provided for this answer.

7,467.

Use the figure above to answer this question. Which of the following compounds is an isomer of the compound

A.

A

B.

B

C.

C

D.

D

Correct answer is D

No explanation has been provided for this answer.

7,468.

The above graph shows a typical heating curve from the solid phase through the liquid phase to the gaseous phase of a substance. Which part of the curve shows solid and liquid in equilibrium?

A.

T

B.

U

C.

X

D.

Y

Correct answer is A

point T shows solid-liquid equilibrium. At this point, the substance been heated has begun to melt but has not completely melted forming a solid liquid mixture.

7,469.

If in the graph above 1 dm 3 of a saturated solution of KCL is cooled from 80°C, the mass of crystals deposited will be [K = 39, Cl = 35.5]

A.

7.45 g

B.

14.90 g

C.

74.50 g

D.

149.00 g

Correct answer is D

Trace the graph to the y-axis to obtain the solubility of the salt at 80°C and at the point where the straight line touches the y-axis, the solubility of the salt at these respective temperatures is 4mol\dm3 and 6mol\dm3 solubility of salt that will crystallize out = 6- 4 = 2mol\dm3 therefore mass of salt deposited = solubility x molar mass of salt 2 x 74.5 = 149.00g

7,470.

The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X(g) + Y(g) → XY(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X(g) + Y(g)

A.

300, 500

B.

500, 300

C.

-300, -500

D.

-500, -300

Correct answer is C

The uncatalysed reverse reaction = 100 - 400 = -300 The calalysed reverse reaction = 100 - 600 = - 500