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