2015 - JAMB Chemistry Past Questions and Answers - page 7
61
N2O4(g)→ 2NO2(g)
In the endothermic reaction above, more products formed will be favored by
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 option: 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
Users' Answers & Comments62
Chlorine gas turns damp starch-iodide paper
A
pink
B
colourless
C
red
D
dark blue
correct option: d
Chlorine turns a damp starch iodide paper into dark blue or blue black.
Users' Answers & Comments63
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 option: 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
Users' Answers & CommentsTotal 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
64
The principal constituent of natural gas is
A
methane
B
ethane
C
propane
D
Butane
correct option: a
Methane CH4.A. is the principal and commercial constituent natural gas. Option B,C,D are also constituent of natural gas but they are not commercial and of economic importance
Users' Answers & Comments65
One note of a hydrocarbon 36g of carbon and its density is 20. The structure of hydrocarbon is (organic chemical)
A
CH3C = CH
B
CH3CH = CH2
C
CH3CH2C = CH
D
CH33CH2CH3
correct option: a
2VD = Rmm
VD = Vapour Density, Rmm = relative
2 × 20 − 40 molecular mass
Mole of carbon − 36/12
= 3
Mole of H2 = 40 − 36
= 4
The compound contains 3mole of carbon and 4 hydrogen
Users' Answers & CommentsVD = Vapour Density, Rmm = relative
2 × 20 − 40 molecular mass
Mole of carbon − 36/12
= 3
Mole of H2 = 40 − 36
= 4
The compound contains 3mole of carbon and 4 hydrogen
66
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 option: 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
Users' Answers & Comments67
5 block elements of the periodic table one made up of
A
groups 1, 2, 3
B
groups 1, and 2
C
group 3
D
group 3 to 7
correct option: b
5 block elements only are made up of group 1 and 2 options A,C,D takes place of the other blocks in the periodic table p,d,f etc.
Users' Answers & Comments68
The oxidation state of oxygen on tetraoxosulphate iv acid is
A
-4
B
-2
C
4
D
-8
correct option: b
In SO4. The state of oxygen oxidation number is -2. Options A,C,D do not belong to the oxidation state in SO4
Users' Answers & Comments69
In the electrolysis of brine the anode is
A
platinum
B
copper
C
zinc
D
carbon
correct option: d
In the industrial of brine carbon is the anode while mercury is the cathode. Options of A, B, C are not used in brine solution because they are alloy of mercury
Users' Answers & Comments70
Calculate the relative molecular mass of Limestone CaCO3, (Ca = 40, C =12, O = 16)
A
56
B
100
C
76
D
90
correct option: b
One molecule of CaCO has 1Ca, 1C and 30 atom relative molecular mass of CaCO3
1 × Ar of Ca +1 × Ar of C +3 × Ar of O
(1 × 40 + 1 × 12 + 3 × 1)
40 + 12 + 48
=100
Option A,C and D will not give 100
Users' Answers & Comments1 × Ar of Ca +1 × Ar of C +3 × Ar of O
(1 × 40 + 1 × 12 + 3 × 1)
40 + 12 + 48
=100
Option A,C and D will not give 100