1998 - JAMB Chemistry Past Questions and Answers - page 2
11
The property used in obtaining oxygen and nitrogen industrially from air is the?
A
boiling point
B
density
C
rate of diffusion
D
solubility
correct option: a
Users' Answers & Comments12
Potassium tetraoxomanganate (VII) is often added to impure water to?
A
reduce organic impurities
B
reduce inorganic impurities
C
destroy bacteria and algae
D
remove permanent hardness
correct option: c
Users' Answers & Comments13
The soil around a battery manufacturing factory is likely to contain a high concentration of?
A
Ca2+ salts
B
Pb2+ salts
C
Mg2+ salts
D
Al3+ salts
correct option: b
Users' Answers & Comments14
Excess phosphorus was burnt in a gas jar and the residual gas passed successively over concentrated KOH solution and concentration H2SO4 before being collected in a flask. The gases collected are?
A
carbon (IV) oxide, nitrogen and the rare gases
B
nitrogen and the rare gases
C
carbon (IV) oxide, nitrogen (IV) oxide and the rare gases
D
carbon (IV) oxide
correct option: c
Users' Answers & Comments15
If an element X of an atomic number Z and mass number Y is irradiated by an intense concentration of neutrons, the relevant nuclear equation is?
A
yzX + 10n → y - 1z + 1X
B
yzX + 10n → y + 1zX
C
yzX + 10n → yz + 1X
D
yzX + 10n → y + 1z - 1X
correct option: b
Users' Answers & Comments16
90.0g of MgCI2 was placed in 50.0cm3 of water to give a saturated solubility of the salt is 8.0 mol dm3 at the same temperature, what is the mass of the salt left undissolved at the given temperature?
(Mg = 24, Cl = 35.5)
(Mg = 24, Cl = 35.5)
A
52.0g
B
58.5g
C
85.5g
D
88.5g
correct option: a
Molar mass of MgCl2 = 95g
The solubility of MgCl2 is 8.0/dm3
1 dm3 = 1000cm3
Solubility of g/cm3
8 x 95 → 1000cm3
x → 50
x = (50)/(1000) x (8 x 95) / (1) = 38g
Mass of the salt left undissolved = 90 - 38 = 52.0g
Users' Answers & CommentsThe solubility of MgCl2 is 8.0/dm3
1 dm3 = 1000cm3
Solubility of g/cm3
8 x 95 → 1000cm3
x → 50
x = (50)/(1000) x (8 x 95) / (1) = 38g
Mass of the salt left undissolved = 90 - 38 = 52.0g
17
Soap lather is an example of a colloid in which a?
A
liquid is dispersed in gas
B
solid is dispersed in liquid
C
gas is dispersed in liquid
D
liquid is despersed in liquid
correct option: c
Users' Answers & Comments18
The pH of a solution obtained by mixing 100cm3 of a 0.2M solution of NaOH is?
A
1.3
B
7.0
C
9.7
D
12.7
correct option: d
Users' Answers & Comments19
Mg2+(aq) + 2e->(aq) → Mg(s)E°(volts) = 2.370
Zn2+(aq) + 2e->(aq) → Zn(s)E°(volts) = -0.763
Cds2+(aq) + 2e->(aq) → Cd(s)E°(volts) = 0.403
Cu2+(aq) + 2e->(aq) → Cu(s)E°(volts) = 0.340
In the electrochemical series above, the strongest reducing agents is?
Zn2+(aq) + 2e->(aq) → Zn(s)E°(volts) = -0.763
Cds2+(aq) + 2e->(aq) → Cd(s)E°(volts) = 0.403
Cu2+(aq) + 2e->(aq) → Cu(s)E°(volts) = 0.340
In the electrochemical series above, the strongest reducing agents is?
A
Cu (s)
B
Cd(s)
C
Znsub>(s)
D
[]
correct option: d
Users' Answers & Comments20
2Cl2(g) + 2H2O(g) 4HCl(g) + O2(g)
∆H° = +115KJ mol-1. In the above equilibrium reaction, a decrease in temperature will?
∆H° = +115KJ mol-1. In the above equilibrium reaction, a decrease in temperature will?
A
favour the reverse reaction
B
favour the forward reaction
C
have no effect on the equilibrium state
D
double the rate of the reverse raection
correct option: a
Users' Answers & Comments