1991 - JAMB Chemistry Past Questions and Answers - page 1
1
Which of the following can be obtained by fractional distillation?
A
Nitrogen from liquid air
B
Sodium chloride from sea water
C
Iodine from a solution of Iondine in carbon tetrachloride
D
Sulphur from a solution of sulphur incarbon disulphide
correct option: a
Users' Answers & Comments2
Which of the following are mixtures?
i, Petroleum
ii, Rubber latex
iii. Vulcanizer's solution
iv, Carbon (II)sulphide
i, Petroleum
ii, Rubber latex
iii. Vulcanizer's solution
iv, Carbon (II)sulphide
A
i, ii and iii
B
i, ii and iv
C
i and ii only
D
i and iv
correct option: a
Users' Answers & Comments3
An iron ore is known to contain 70.0% Fe2O3. The obtain from 80kg of the ore is?
(Fe = 56, O = 16)
(Fe = 56, O = 16)
A
35.0 kg
B
39.2 kg
C
70.0 kg
D
78.4 kg
correct option: b
2Fe2O3 → 4Fe + 3O2
320g 224g 96g
(70) / (100) x (80) / (1) 56g
if 0.32kg of Fe293 contains 0.224 kg
Then 56kg will contain (56 x 0.224) / (0.32) =39.2 kg
Users' Answers & Comments320g 224g 96g
(70) / (100) x (80) / (1) 56g
if 0.32kg of Fe293 contains 0.224 kg
Then 56kg will contain (56 x 0.224) / (0.32) =39.2 kg
4
In two separate experiments, 0.36g and 0.71g of chlorine combined with a metal X to give Y and Z respectively. An analysis showed that Y and Z contain 0.20g and 0.40g of X respectively. The data above represents the law of ?
A
multiple proportion
B
conservation of mass
C
constant composition
D
reciprocal proportion
correct option: c
0.36g of Cl combines with 0.2g of x
1g of Cl will combine with \(\frac{1 \times 0.2}{0.32}\) = 0.56
0.71g of U combines with 0.49g of x
1g of U will combine with \(\frac{1 \times 0.4}{71}\) = 0.56
Ratio 0.56 : 0.56 = 1:1
Users' Answers & Comments1g of Cl will combine with \(\frac{1 \times 0.2}{0.32}\) = 0.56
0.71g of U combines with 0.49g of x
1g of U will combine with \(\frac{1 \times 0.4}{71}\) = 0.56
Ratio 0.56 : 0.56 = 1:1
5
30cm3 of oxygen at 10 atmospheres pressure is placed in a 20 dm3 container. Calculate the new pressure if temperature is kept constant?
A
6.7 atm
B
15.0 atm
C
60.0 atm
D
66. 0 atm
correct option: b
Users' Answers & Comments6
Calculate the volume of carbon (IV)oxide measured at s.t.p, produced when 1 kg of potassium hydrogen trioxocarbonate (IV) is totally decomposed by heat?
(G.M.V. at s.t.p 22.4 dm3, K = 39, O = 16, C = 12, H = 1)
(G.M.V. at s.t.p 22.4 dm3, K = 39, O = 16, C = 12, H = 1)
A
28 dm3
B
56 dm3
C
112 dm3
D
196 dm3
correct option: c
2KHCOdm3 → K2CO3 + H2O + CO2
2(39 + 1 + 12 + 48) 22.4 dm3
200 g 22.4 dm3 of CO2
1000 g (1000) / (200) x 22.4 = 112 dm3
Users' Answers & Comments2(39 + 1 + 12 + 48) 22.4 dm3
200 g 22.4 dm3 of CO2
1000 g (1000) / (200) x 22.4 = 112 dm3
7
A given quantity of a gas occupies a volume of 228 cm3 at a pressure of 750mm Hg. What will be its volume at atmospheric pressure?
A
220 cm3
B
225 cm3
C
230 cm3
D
235 cm3
correct option: b
P1V1 = P2V2 ∴ 750 x 228 = 760 V2
V2 = (750 x 228 cm3) / (760) = 225 cm3
Users' Answers & CommentsV2 = (750 x 228 cm3) / (760) = 225 cm3
8
A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm3 container at 20°C. The number of moles of gas in the sample is?
(R = 0.082 litre atm / deg mole)
(R = 0.082 litre atm / deg mole)
A
1.00
B
2.00
C
3.00
D
4.00
correct option: a
PV = nRT
2.93 x 8.2 = 0.082 x 293 xn
∴ n = (2.93 x8.2) / (0.082 x 293)
n = 1
Users' Answers & Comments2.93 x 8.2 = 0.082 x 293 xn
∴ n = (2.93 x8.2) / (0.082 x 293)
n = 1
9
Atoms of element X (with 2 electrons in the outer shell). combine with atoms of Y (with 7 electrons in the outer shell). Which of the following statements is FALSE? The compound formed?
A
has formula XY
B
is likely to be ionic
C
contains X2+ ions
D
contains Y ions
correct option: a
Users' Answers & Comments10
The electronic configuration of an elements is 1s22s22p63s23p3. How many unpaired electrons are there in the element?
A
5
B
4
C
3
D
2
correct option: c
Users' Answers & Comments