JAMB Past Questions and Answers - Page 1422

7,106.

In the electrolysis of CuSo4(g) using platinum electrode the reaction at the anode is

A.

4H+ 4e - 2H2

B.

4OH= 4e- + 2H2O + O2

C.

2OH - 2e- = 2OH

D.

2OH- + 2OH = 2H2O + O2

Correct answer is B

40H − 4e → 2H2O + O2is the reaction of sun at the anode in the electrolysis of CuSO4 (g) using platinum particles. Option A,C,D are not formed as a result of the equation

7,107.

Chlorine consisting of two isotope of mass number 35 and 37 in the ratio 3:1 has an atomic mass of 35.5. Calculate the relative abundance of the isotope of mass number 37

A.

20

B.

25

C.

60

D.

75

Correct answer is B

Let the relative abundance of the energy with mass 37 be
Total relative abundance of the isotope of mass 359100-k)
Total mass of isotope of mass 37-37x, while that of 35-359(100x)
-37x + 3500 − 35 − 35.5
-37x + 3500 − 35n − 35.5
Mean mass of chlorine atom − (2n + 3500)/ ÷ 100
= 35.5
2x + 3500 − 3550yx = 50/2

7,108.

Chlorine gas turns damp starch-iodide paper

A.

pink

B.

colourless

C.

red

D.

dark blue

Correct answer is D

Chlorine turns a damp starch iodide paper into dark blue or blue black.

7,109.

N2O4(g)→ 2NO2(g)

In the endothermic reaction above, more products formed will be favored by

A.

A constant values

B.

an increase in pressure

C.

a decrease pressure

D.

a decrease volume

Correct answer is C

A decrease in pressure will result in the breaking or splitting of a larger molecule into a simpler ones. Options A, B, D are not in conformance to the reaction

7,110.

what is the pH of 0.00lmoldm3 solution of sodium hydroxide

A.

14

B.

13

C.

12

D.

11

Correct answer is D

[H+][OH−] = 10 − 4
[H+] =10 − 14 ÷ [OH+]
=10 −14 ÷ (1 × 10 − 3) = 10 − 11
pH = − log10[H+ ]
= − log10[10 − 11] = − 1 × −11
log10[10 − 11] = 1
= − 1 × 11 × 1
= − 11