A mixture of iodine and sulphur crystals can be separated by treatment with?
отговор
(B)
carbon (IV) sulphide to filter off iodine
2
Sieving is a technique used to separate mixture containing solid particles of
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(C)
different sizes
3
Which of the following compounds is composed of Al, Si, O and H?
отговор
(C)
Clay
4
50 cm3 of carbon (II) oxide was exploded with 150 cm3 of air containing 20% oxygen by volume. Which of the reactants was in excess?
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(C)
Oxygen
5
How many moles of HCl will be required to react with potassium heptaoxodichromate (VI) to produce 3 moles of chlorine?
отговор
(A)
14
6
The ratio of the initial to final pressure of a given mass of gas is 1:1.5. Calculate the final volume of the gas if the initial volume was 300 cm3 at the same temperature
отговор
(B)
200 cm3
7
The partial pressure of oxygen in a sample of air is 452 mm Hg and the total pressure is 780 mm Hg. What is the mole fraction of oxygen?
отговор
(B)
0.579
8
The fundamental difference between the three states of matter is the
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(D)
degree of movement of their particles
9
Which of the following statement is correct about the periodic table?
отговор
(B)
The valence electron of the elements in the same period increase progressively across the period
10
The electron configuration of \(_{22}X^{2+}\) ion is
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(D)
1s2 2s22p6 3s2 3p6 3d2
11
Which of the following types of bonding does not involve the formation of new substance?
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(A)
Metallic
12
The knowledge of half-life can be used to
отговор
(B)
detect an element
13
The shapes of CO\(_2\), H\(_2\)O and CH\(_4\) respectively are
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(C)
linear, bent and tetrahedral
14
The distance between the nuclei of chlorine atoms in a chlorine molecule is 0.194 mm. The atomic radius of chlorine atom is
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(A)
0.097 mm
15
The noble gas, argon,is used for
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(A)
electric arc welding
16
A side effect of soft water is that
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(C)
it attacks lead contained in pipes
17
Water molecule can be ligands especially when they are bonded to
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(C)
transition metals
18
The air pollutant unknown in nature is
отговор
(D)
DDT
19
1.0 dm3 of distilled water was used to wash 2.0g of a precipitate of AgCl. If the solubility product of AgCl is 2.0 x 10\({^-10}\)moldm-6, what quantity of silver was lost in the process?
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(D)
1.414 * 10-5mol dm-3
20
Hydration of ions in solution is associated with
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(D)
liberation of heat
21
HCl(aq) + H\(_2\)O(l) → H\(_3\)O+(aq) + Cl\(^-\)(aq)
In the reaction above, Cl\(^-\)(aq) is the
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(C)
conjugate base
22
In which order are the following salts sensitive to light?
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(D)
AgCl > AgBr > Agl
23
The pOH of a solution of 0.25 mol dm\(^{-3}\) of hydrochloric acid is
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(B)
13.40
24
MnO\(_{4(aq)}^{-1}\) + 8H\(^+ _{(aq)}\) + Y → Mn\(^{2+} _{(aq)}\) + 4H\(_2\)O\(_{(l)}\)
Y in the equation above represents
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(C)
5e-
25
(1/2)Zn2+(aq) + e- → (1/2) Zn(s)
In the reaction above, calculate the quantity of electricity required to discharge zinc.
[F = 96 500 C mol-1]
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(C)
9.650 x 104C
26
Given that M is the mass of substance deposited in an electrolysis and Q the quantity of electricity consumed, then Faraday's law can be written as
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(D)
M = QZ
27
0.46g of ethanol when burned raised the temperature of 50g of water by 14.3K. Calculate the heat of combustion of ethanol.
[C = 12, O = 16, H = 1, Specific heat capacity of water = 4.2 jg-1K-1]
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(C)
-300 KJ mol-1
28
Powdered marble reacts faster with hydrochloric acid solution than the granular form because the powdered form has
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(C)
larger surface area
29
N2(g) + O2(g) ↔ 2NO(g); ΔH = + 180.6 kJ mol-1
In the reaction above, increase in temperature will
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(B)
increase in the yield of NO
30
For a reaction in equilibrium, the species involved in the equilibrium constant expression are
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(D)
gaseous and dissolved species
31
A phenomenon where an element exist in different forms in the same physical state is known as
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(C)
allotropy
32
The substance often used for vulcanization of rubber is
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(C)
sulphur
33
A gas that is not associated with global warming is
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(D)
H2
34
The refreshing and characteristic taste of soda water and other soft drinks is as a result of the presence in them of
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(A)
carbon (IV) oxide
35
A form of carbon used for absorbing poisonous gases and purification of noble gases is
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(A)
wood charcoal
36
Synthesis gas is a mixture of
отговор
(D)
CO and H2
37
Potassium vapour burns with a
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(C)
violet flame
38
A common characteristics of copper and silver in their usage as coinage metals is that they
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(B)
are not easily oxidized
39
Haematite is an ore of
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(C)
iron
40
The least easily oxidized of the metals below is?
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(C)
Zn
41
The repeating unit in natural rubber is
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(B)
isoprene
42
Unsaturated organic compounds are identified by decolourization of
отговор
(B)
bromine water and acidified potassium tetraoxomanganate (VII) solution
43
The conditions necessary for the extraction of a water molecule from two molecules of ethanol are
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(C)
excess acid and a higher temperature
44
The chlorinated alkane often used industrially to remove grease is
