Which of the following methods can be used to obtain pure water from a mixture of sand, water and methanoic acid?
отговор
(D)
filtration followed by distillation
2
How many atoms are present in 6.0g of magnesium?
[Mg = 24, NA = 6.02 x 1023 mol-1]
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(C)
1.51 x 1023
3
50 cm\(_3\) of gas was collected over water at 10ºC and 765 mm Hg. Calculate the volume of the gas at s.t.p. if the saturated vapour pressure of water at 10ºC is 5mm Hg
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(D)
48.23 cm 3
4
An increase in the pressure exerted on gas at a constant temperature results in
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(B)
a decrease in volume
5
2H2(g) + O2(g) → 2H2 O(g)
In the reaction above, what volume of hydrogen would be left over when 300 cm3 of oxygen and 1000 cm3 of hydrogen are exploded in a sealed tube?
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(B)
400 cm3
6
l . Evaporation. ll. Sublimation. lll. Diffusion. IV. Brownian motion.
Which of the above can correctly be listed as evidences for the particulate nature of matter?
отговор
(D)
l, ll, lll and lV
7
If the elements X and Y have atomic numbers 11 and 17 respectively, what type of bond can they form?
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(C)
Ionic
8
A hydrogen atom which has lost an electron contains
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(A)
one proton only
9
The electronic configuration of Mg 2+ is
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(B)
Is22s22P6
10
Group VII elements are
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(B)
good oxidizing agents
11
Which of the following is used to study the arrangement of particles in crystal lattices?
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(D)
X-rays
12
I. It has a varied composition from one place to another. ll. it constituents can be separated by physical means
lll. It contains unreactive noble gases
which of the above shows that air is a mixture?
отговор
(D)
l,ll and lll
13
The chemicals used to soften hard water involves the addition of
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(C)
solube sodium compounds which from insoluble precipitates of calcium and magnesium ions
14
Chlorination of water for town supply is carried out to
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(B)
remove germs from the water
15
The solubilites of different solutes in a given solvent can be compared by
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(B)
plotting their solubility curves on the same axes
16
Potassium trioxochlorate (V)has a solubility of 1.5 mol dm -3 at 45 oC.On cooling this solution to a temperature of 20 oC, the solubility was found to be 0.5 mol dm -3. What mass of KCIO 3 was crystalized out?
[K = 39, Cl = 35.5 O =16]
отговор
(D)
122.50g
17
Which of the following pollutants is associated with brain damage?
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(A)
Carbon (ll) oxide
18
Which of the following will produce a solution with pH less than 7 at equivalent point?
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(C)
HCL +Mg (OH) 2
19
The number of hydroxonium ions produced by one molecule of an acid in aqueous solution is its
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(A)
basicity
20
During a titration experiment, 0.05 moles of carbon (lV) oxide is liberated. What is the volume of gas liberated?
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(D)
1.12 dm 3
21
A major factor considered in selecting a suitable method for preparing a simple salt is its
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(D)
solubility in water
22
The oxidation number of boron in NaBH 4 is
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(D)
+3
23
\(Na_2O_{2(s)} + H_2O_{(1)}\)→ \(NaOH_{(s)} +O_{2(g)}\)
The substance that is oxidized in the reaction above is
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(C)
H2O(1)
24
What number of moles of Cu 2+ will be deposited by 360 coulombs of electricity?
[f = 96500 C mol -1]
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(B)
1. 87 x 10 10 -3 mole
25
A metal M displaces zinc from ZnCl solution
This shows that
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(B)
M is more electropositive than zinc
26
CO(g) + H\(_2\) O\(_{(g)}\) → CO\(_{2(g)}\) + H\(_{2(g)}\)
Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO\(_{2(g)}\), H\(_2\)O\(_{(g)}\) and CO\(_{(g)}\) in kJmol\(^{-1}\) are - 394, -242 and - 110 respectively.
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(D)
- 42 KJ mol -1
27
An increase in entropy can best be illustrated by
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(A)
mixing of gases
28
The highest rate of production of carbon (lV) oxide can be achieved using
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(C)
0.10 mol -3HCI and 5g powdered CaCO3
29
A piece of filter paper moistened with lead (ll) ethanoate solution turns black when the paper is dropped into a gas likely to be
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(D)
hydrogen sulphide
30
Which of the following gases has a characteristic pungent smell, turns red litmus paper blue and forms dense white fumes with hydrogen chloride gas?
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(D)
NH3
31
Commercial bleaching can be carried out using
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(C)
chlorine and sulphur (IV) oxide
32
Mineral acids are usually added to commercial hydrogen peroxide to
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(C)
minimize its decomposition
33
Which of the following compounds will burn with a brick-red colour in a non-luminous Bunsen flame?
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(C)
CaCl2
34
The purest form of iron which contains only about 0.1% carbon is
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(B)
wrought iron
35
A common characteristic between zinc and the other transition elements is the ability to
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(B)
from complex ions
36
Which of the following metals is the least reactive?
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(D)
Au
37
Geometric isomerism can exist in
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(A)
hex-3-ene
38
Alkanals can be distinguished from alkanones by the reaction with
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(D)
fehling's solution
39
The isomers of C3H8O ARE
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(A)
1 - propanol and 2 - propanol
40
Carbohydrates are large molecules with the molecular formula C\(_x\)(H\(_2\)O)\(_y\). In which of the following pairs is x not equal to y?
