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