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?
Odpowiedź
(C)
Z
2
What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?
[H = 1, O = 16]
Odpowiedź
(C)
72.0g
3
A particle that contains 9 protons, 10 neutrons and 10 electrons is a
Odpowiedź
(A)
negative ion
4
Cancerous growths are cured by exposure to
Odpowiedź
(A)
γ - rays
5
An oxide XO\(_2\) has a vapour density of 32. What is the atomic mass of X?
Odpowiedź
(A)
32
6
Millikan's contributions to the development of atomic theory is the determination of
Odpowiedź
(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?
Odpowiedź
(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
Odpowiedź
(B)
18
9
Which of the following statements is correct about the average kinetic energy of the molecules of a gas?
Odpowiedź
(C)
It increase with increase in temperature
10
The pollution from petroleum spillage in rivers and lakes can best be dispersed by
Odpowiedź
(B)
Passing of ships through the area
11
Deliquescent substances are used for
Odpowiedź
(D)
Drying
12
Pure solvents are obtained by
Odpowiedź
(A)
Distillation
13
What is the decrease in volume of air when pyrogallol is shaken with 30.00cm\(^3\) of air ?
Odpowiedź
(B)
6.30cm3
14
Environmental pollution is worsened by the release from automobile exhausts of?
Odpowiedź
(C)
Smoke
15
The chemical used for coagulation in water purification is
Odpowiedź
(A)
Aluminium tetraoxosulphate (VI)
16
Phosphorus is stored under water to prevent it from
Odpowiedź
(D)
Catching fire
17
In which of the following reactions does reduction takes place
Odpowiedź
(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?
Odpowiedź
(C)
Removing some S
19
A metal M displaces zinc from zinc chloride solution. This shows that
Odpowiedź
(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?
Odpowiedź
(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]
Odpowiedź
(C)
4
22
Ethanoic acid is
Odpowiedź
(C)
monobasic
23
C(s) + 2S(g) → CS\(_2\)(g)
ΔH = +89 kJ mol-1
The chemical equation above implies that
Odpowiedź
(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?
Odpowiedź
(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
Odpowiedź
(D)
a reducing agent
26
When ΔH is negative, a reaction is said to be
Odpowiedź
(C)
exothermic
27
As the concentration of an electrolyte reduces, the conductivity
Odpowiedź
(B)
decreases
28
In which of the following reactions has the oxidation number of nitrogen increased?
Odpowiedź
(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
Odpowiedź
(A)
negative
30
Fermentation is the
Odpowiedź
(B)
conversion of sugar to alcohol in the presence of yeast
31
The general formula for the alkanals is
Odpowiedź
(D)
RCHO
32
The main impurity in iron ore during the extraction of iron is
Odpowiedź
(A)
Silicon (IV) oxide
33
During the vulcanization of rubber, sulphur is added to
Odpowiedź
(C)
Bind rubber molecules together
34
Catalytic hydrogenation of benzene produces
Odpowiedź
(C)
Cyclohexane
35
A trihydric alkanol is
Odpowiedź
(A)
Glycerol
36
When chlorine Is passed into water and the resulting solution exposed to sunlight, the product formed are
Odpowiedź
(D)
Hydrochloric acid and oxygen
37
Proteins in acid solution undergo
Odpowiedź
(D)
Hydrolysis
38
A characteristic reaction of the compounds with the general formula C\(_n\)H\(_{2n}\) is
Odpowiedź
(B)
Polymerization
39
The pair of organic compounds that are isomers is
Odpowiedź
(D)
But-1-ene and but-2-ene
40
A burning candle produces water and
Odpowiedź
(B)
Carbon (IV) oxide
41
The gas that can best be collected by downward displacement of air is
Odpowiedź
(C)
Ammonia
42
Which of the following metals burn with brick red flame?
Odpowiedź
(B)
Ca
43
Which of the following represent hybridization in ethyne?
Odpowiedź
(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
Odpowiedź
(A)
A dehydrating agent
45
When sodium reacts with water, the resulting solution is
