25cm\(^3\) of a gas X contains Z molecules at 15\(^0\)C and 75 mmHg. How many molecules will 25cm\(^3\) of another gas Y contain at the same temperature and pressure?
Răspuns
(C)
Z
2
What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?
[H = 1, O = 16]
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(C)
72.0g
3
A particle that contains 9 protons, 10 neutrons and 10 electrons is a
Răspuns
(A)
negative ion
4
Cancerous growths are cured by exposure to
Răspuns
(A)
γ - rays
5
An oxide XO\(_2\) has a vapour density of 32. What is the atomic mass of X?
Răspuns
(A)
32
6
Millikan's contributions to the development of atomic theory is the determination of
Răspuns
(A)
charge on electron
7
Four elements W, X, Y and Z have atomic number 2,6,16 and 20 respectively. Which of these elements is a metal?
Răspuns
(C)
Z
8
An element X with relative atomic mass 16.2 contains two isotopes \(^{16}_{8}\)X with relative abundance of 90% and \(^{m}_{8}\)X with relative abundance of 10%. The value of m is
Răspuns
(B)
18
9
Which of the following statements is correct about the average kinetic energy of the molecules of a gas?
Răspuns
(C)
It increase with increase in temperature
10
The pollution from petroleum spillage in rivers and lakes can best be dispersed by
Răspuns
(B)
Passing of ships through the area
11
Deliquescent substances are used for
Răspuns
(D)
Drying
12
Pure solvents are obtained by
Răspuns
(A)
Distillation
13
What is the decrease in volume of air when pyrogallol is shaken with 30.00cm\(^3\) of air ?
Răspuns
(B)
6.30cm3
14
Environmental pollution is worsened by the release from automobile exhausts of?
Răspuns
(C)
Smoke
15
The chemical used for coagulation in water purification is
Răspuns
(A)
Aluminium tetraoxosulphate (VI)
16
Phosphorus is stored under water to prevent it from
Răspuns
(D)
Catching fire
17
In which of the following reactions does reduction takes place
Răspuns
(D)
2H+ + 2e- → H2
18
P(g) + Q(g) ↔ 3R(s) + S(g) ΔH is negative
Which of the following will increase the yield of R?
Răspuns
(C)
Removing some S
19
A metal M displaces zinc from zinc chloride solution. This shows that
Răspuns
(C)
M is more electropositive than zinc
20
Which of the following best explains the increase in the rate of a chemical reaction as the temperature rises?
Răspuns
(D)
The collision frequency of the molecules increase
21
What current in amperes will deposit 2.7g of aluminium in 2 hours?
[Al = 27, F = 96 500 C mol-1]
Răspuns
(C)
4
22
Ethanoic acid is
Răspuns
(C)
monobasic
23
C(s) + 2S(g) → CS\(_2\)(g)
ΔH = +89 kJ mol-1
The chemical equation above implies that
Răspuns
(D)
89 kJ of energy is absorbed
24
2SO\(_2\)(g) + O\(_2\)(g) ↔ 2SO\(_3\)(g)
ΔH = -189 kJ mol-1
The equilibrium constant for the reaction above is increased by?
Răspuns
(A)
decreasing the temperature of the system
25
3Cu(s) + 8HNO\(_3\)(aq) → 3Cu(NO\(_3\))\(_2\)(aq) + 4H\(_2\)O(l) + 2NO(g)
In the equation above, copper is
Răspuns
(D)
a reducing agent
26
When ΔH is negative, a reaction is said to be
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(C)
exothermic
27
As the concentration of an electrolyte reduces, the conductivity
Răspuns
(B)
decreases
28
In which of the following reactions has the oxidation number of nitrogen increased?
Răspuns
(B)
2NO(g) + O2(g) → 2NO2(g)
29
NH\(_3\)\(_{(g)}\) + HCl\(_{(g)}\) → NH\(_4\)Cl\(_{(s)}\)
The entropy change in the system above is
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(A)
negative
30
Fermentation is the
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(B)
conversion of sugar to alcohol in the presence of yeast
31
The general formula for the alkanals is
Răspuns
(D)
RCHO
32
The main impurity in iron ore during the extraction of iron is
Răspuns
(A)
Silicon (IV) oxide
33
During the vulcanization of rubber, sulphur is added to
Răspuns
(C)
Bind rubber molecules together
34
Catalytic hydrogenation of benzene produces
Răspuns
(C)
Cyclohexane
35
A trihydric alkanol is
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(A)
Glycerol
36
When chlorine Is passed into water and the resulting solution exposed to sunlight, the product formed are
Răspuns
(D)
Hydrochloric acid and oxygen
37
Proteins in acid solution undergo
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(D)
Hydrolysis
38
A characteristic reaction of the compounds with the general formula C\(_n\)H\(_{2n}\) is
Răspuns
(B)
Polymerization
39
The pair of organic compounds that are isomers is
Răspuns
(D)
But-1-ene and but-2-ene
40
A burning candle produces water and
Răspuns
(B)
Carbon (IV) oxide
41
The gas that can best be collected by downward displacement of air is
Răspuns
(C)
Ammonia
42
Which of the following metals burn with brick red flame?
Răspuns
(B)
Ca
43
Which of the following represent hybridization in ethyne?
Răspuns
(D)
Sp
44
\(C_{12}H_{22}O_{11(s)} + H_2SO_{4(aq)} → 12C(s) + 11H_2O(l) + H_2SO_{4(aq)}\)
In the reaction above, tetraoxosulphate (VI) acid function as
Răspuns
(A)
A dehydrating agent
45
When sodium reacts with water, the resulting solution is
