1995 - JAMB Chemistry Past Questions and Answers - page 3
21
Which of the following is a redox reaction?
A
KCI(aq) + H2SO4(aq) → KHSO4(aq) + HCI(aq)
B
2FeBr2(aq) + Br4(aq) → 2FeBr3(aq)
C
3AgNO(aq) + FeCl3(aq) → 3AgCl(aq) + Fe(NO3)3(aq)
D
H2CO3(aq) → H2O(I)2- + CO2(g)
correct option: b
Users' Answers & Comments22
Cr2O72-(aq) + 14H+(aq) + 6l-(aq) → 2Cr3+(aq) + 3l(g) + 7H2O(I).
The change in the oxidation number of oxygen in the equation above is?
The change in the oxidation number of oxygen in the equation above is?
A
0
B
1
C
2
D
7
correct option: a
Users' Answers & Comments23
If an equilibrium reaction has ∆H < O, the reaction will proceed favorably in the forward reaction at?
A
low temperatures
B
high temperatures
C
all temperatures
D
all pressures
correct option: a
Users' Answers & Comments24
Which of the following processes leads to increase in entropy?
A
Mixing a sample of NaCl and sand
B
Condensation of water vapour
C
Boiling a sample of water
D
Cooling a saturated solution
correct option: c
Users' Answers & Comments25
Which of the following equilibria is shifted to the right as a result of an increase in pressure?
A
H2(g) + I2(g) 2HI(g)
B
2NO2(g) N2O4(g)
C
PCl5(s) PCl3(s) + Cl2(g)
D
2O3(g) 3O2(g)
correct option: b
Users' Answers & Comments26
In the industrial production of hydrogen from natural gas, carbon (IV) oxide produced along with the hydrogen is removed by?
A
washing under pressure
B
passing the mixture into lime water
C
using ammoniacal copper (l) chloride
D
drying over phoshorus (V) oxide
correct option: c
Users' Answers & Comments27
Sulphur exists in six forms in the solid state. This property is known as?
A
isomerism
B
allotropy
C
isotopy
D
isomorphism
correct option: b
Users' Answers & Comments28
A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?
A
sulphur (lV) oxide
B
hydrogen sulphide
C
sulphide (lV) oxide
D
hydrogen chloride
correct option: a
Users' Answers & Comments29
Which of the following ions will give a white precipitate with aqueous NaOH and soluble in excess of the base?
A
Ca2+
B
Mg2+
C
Zn2+
D
Cu2+
correct option: c
Users' Answers & Comments30
In the extraction of iron in the blast furnace, limestone is used to?
A
release CO2 for the reaction
B
reduce the iron ore
C
increase the strenght of the iron
D
remove impurities
correct option: d
Users' Answers & Comments