Which of the following would support the conclusion that a solid sample is a mixture?
Trả lời
(C)
the solid has a melting range of 300oC to 375oC
2
The molar ratio of carbon to hydrogen of a volatile liquid compound is 1: 2. 0. 12 g of the liquid on evaporation at s.t.p. gave 32 cm3 of vapour. The molecular formula of the liquid is
[G.M.V =22.4 dm 3, C = 12, H = 1]
Trả lời
(D)
C 6H 12
3
20.00 cm\(^3\) of a solution containing 0.53 g of anhydrous Na\(_2\)CO\(_3\) in 100 cm\(^3\) requires 25.00 cm\(^3\) of H\(_2\)SO\(_4\) for complete neutralisation. The concentration of the acid solution in moles per dm\(^3\) is [H =1, C = 12, O = 16, Na =23, S = 32]
Trả lời
(B)
0.04
4
The minimum volume of oxygen required for the complete combustion of a mixture of 10cm 3 of CO and 15 cm 3 of H 2 is
Trả lời
(B)
12.5 cm3
5
What is the partial pressure of hydrogen gas collected
over water at standard atmospheric pressure and 25 oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature?
Trả lời
(A)
737 mm Hg
6
The atomic radius of Li, Na and K are 1: 33A, 1. 54A and 1. 96A res pectively. Which of the following explaqins this gradation in atomic radius?
Trả lời
(C)
the number of the electron shells increases from Li to Na to K
7
Elements X and Y have electronic configurations 1s\(^2\)2s\(^2\)2p\(^4\) and 1s\(^2\)2s\(^2\)2p\(^6\)3s\(^2\)3p\(^1\) respectively. When they combine, the formula of the compound formed is?
Trả lời
(D)
Y2X3
8
The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains
Trả lời
(B)
55 protons and 78 neutrons
9
Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas?
Trả lời
(B)
Q
10
How many valence electrons are contained in the element represented \(^{31}\) \(_{15}\)P?
Trả lời
(B)
5
11
The gaseous pollutant sulphur (IV)oxide is most likely to be detected in fairly reasonable quantities in the area around a plant for the
Trả lời
(C)
smelting of copper
12
Calcium hydroxide is added in the treatment of town water supply to
Trả lời
(B)
facilitate coagulation of organic particles
13
A hydrated salt of formula MSO4.xH2 O CONTAINS 45.3% by mass of water of crystalisation. Calculate the value of x [M = 56, S = 32, O = 16, H = 1 ]
Trả lời
(C)
7
14
Using 50 cm\(^3\) of 1 M potassium hydroxide and 100 cm\(^3\) of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm\(^3\) of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [K = 39, S = 32, O = 16, H = 1]
Trả lời
(C)
50, 25
15
A solution of calcium bromide contains 20 g dm\(^3\). What is the molarity of the solution with respect to calcium bromide and bromide ions? [Ca = 40, Br = 80]
Trả lời
(B)
0. 1, 0. 2
16
The substance ZnO dissolves in sodium hydroxide solution and mineral acid solution to give soluble products in each case. ZnO is therefore referred to as
Trả lời
(B)
an amphoteric oxide
17
An acid and its conjugate base
Trả lời
(B)
differ only by a proton
18
The same current is passed for the same time through solutions of AgNO3 and CuSO4 connected in series. How much silver will be deposited if 1.0 g of copper is produced?
[Cu = 63.5, S = 32, O = 16, Ag = 108, N = 14]
Trả lời
(B)
3.4 g
19
What is discharged at the cathode during the electrolysis of copper (ll) tetraoxosulphate (VI) solution?
Trả lời
(A)
Cu 2+ only
20
An element, Z froms an anion whose formula is [Z(CN)6]y. If Z has an oxidation number of +2, what is the value of y?
Trả lời
(C)
- 4
21
The combustion of ethene, C 2H 4, is given by the equation C 2H 4 + 30 2 → 2CO2 + 2H2 O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ
Trả lời
(D)
+ 64
22
Which of the following represents the balanced equation for the reaction of copper with concentrated trioxonitrate (V) acid?
Trả lời
(B)
Cu (s) + 4HNO 3(aq) → Cu (NO 3) 2(aq) + 2H 2O (1) + 2NO 2(g)
23
The catalyst used in the contact process for the manufacture of tetraoxosulphate (VI) acid is
Trả lời
(C)
vanadium (V) oxide
24
Some products of destructive distillation of coal are?
Trả lời
(D)
coke and ammoniacal liquor
25
Gunpower is made from charcoal, sulphur and potassium trioxonitrate (V) The salt in the mixture performs the function of
Trả lời
(A)
an oxidant
26
Which of the following reactions is (are) feasible?
I Br (l) + 2CI\(_2\)(aq) → 2Br(aq) + CI\(_2\)(g)
ll 2 I (aq) + Br\(_2\)(L) → 2Br (aq) + I\(_2\)(s)
lll 2F (aq) + CI\(_2\)(g) → 2CI (aq) + F\(_2\)(g)
IV 2F(aq) + Br\(_2\)(l) → 2Br (aq) + F\(_2\)(g)
Trả lời
(B)
ll
27
Bleaching powder, CaOCI2, H2O, deteriorates on exposure to air because
Trả lời
(C)
carbon (IV) oxide of the atmosphere displaceschlorine from it
28
The products of the thermal decomposition of ammonium trioxonitrate (V) are
Trả lời
(D)
N2O and water
29
The scale of a chemical balance is made of iron plate and coated with copper electrolytically because
Trả lời
(C)
copper is less susceptible to corrosion than iron
30
A metal is extracted from its ore by the electrolysis of its molten chloride and it displaces lead from lead (ll) trioxonitrate (V) solution. The metal is
Trả lời
(D)
sodium
31
Mortar is NOT used for under-water construction because
Trả lời
(A)
it hardens by lose of water
32
Which of the following is NOT involved in the extraction of metals from their ores?
Trả lời
(D)
oxidation with oxidizing agents
33
When excess chlorine is mixed with ethene at room temperature, the product is
Trả lời
(A)
1,2 - dichloroethane
34
Vulcanization of rubber is a process by which
Trả lời
(C)
sulphur is chemically combined in the rubber
35
The reaction between ethanoic acid and sodium hydroxide is an example of
Trả lời
(B)
neutralization
36
The bond which joins two ethanoic acid molecules in the liquid state is
Trả lời
(D)
a hydrogen bond
37
The alkaline hydrolysis of fats and oils produces soap and
Trả lời
(B)
propane - 1,2,3 - triol
38
The gas responsible for most of the fatal explosions in coal mines is
Trả lời
(D)
methane
39
Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature?
Trả lời
(C)
X
40
It can be deduced from the vapour pressure curves above that
Trả lời
(C)
liquid lll has the highest boiling point
41
In the above set up substances X and Y are respectively
Trả lời
(C)
potassium hydroxide and alkaline pyrogallol
42
Which of the curves in the above graph illustrates the behaviour of an ideal gas?
Trả lời
(C)
Y
43
The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X(g) + Y(g) → XY(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X(g) + Y(g)
Trả lời
(A)
300, 500
44
If in the graph above 1 dm 3 of a saturated solution of KCL is cooled from 80°C, the mass of crystals deposited will be
[K = 39, Cl = 35.5]
Trả lời
(D)
149.00 g
45
The above graph shows a typical heating curve from the solid phase through the liquid phase to the gaseous phase of a substance. Which part of the curve shows solid and liquid in equilibrium?
