An element X has 127 neutrons and 82 electrons.
Its atomic number is?
Trả lời
(D)
82
2
When a bottle of Coca-Cola is opened, bubbles of evolve. The gas is?
Trả lời
(C)
carbon dioxide
3
When glowing splint is inserted into the mouth of a jar containing a gas, the splint is extinguished. The gas gives a white precipitate when passing into barium hydroxide. The gas is?
Trả lời
(E)
carbondioxide
4
An example of a strong electrolyte is?
Trả lời
(D)
sodium formate
5
The oxidation number of manganese in KMnO4 is?
Trả lời
(D)
+7
6
Methane is member of the homologous series called?
Trả lời
(D)
alkanes
7
For iron to rust, there should be present?
Trả lời
(D)
oxygen and moisture
8
The mass number of an atom is?
Trả lời
(E)
the sum of numbers of proton and neutrons in the nucleus of the atom
9
Sodium and potassium belong to the same group of the Periodic Table. This is because?
Trả lời
(D)
both have identical electronic configuration
10
Oxidation is the process of?
Trả lời
(B)
loss of electrons
11
the number of atoms in one mole of a substance is equal to?
Trả lời
(B)
the avogadro number
12
Which of the following statements is NOT true of electrovalent compounds?
Trả lời
(D)
The elements forming the compounds normally have their valency electrons in a shared state
13
If concentrated sulphric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mas of carbon. In this reaction, concentrated sulphuric acid is acting as ?
Trả lời
(C)
a dehydrated agent
14
In the reaction
C + 2HNO3 → CO2 + NO2 + NO + H2O nitric acid is acting as?
Trả lời
(C)
an oxidizing agent
15
The brown coloration in nitric acid prepared in the laboratory can be removed by?
Trả lời
(B)
bubbling air through the acid
16
Which of the following processes takes place during electrolysis?
Trả lời
(D)
Negative ions are discharge at the anode by losing sufficient electrons to become neutral
17
In the preparation of ammonia, which of the following is used as the drying agent?
Trả lời
(A)
CaO
18
Which of the following can have an isomer?
Trả lời
(B)
C4H10
19
Allotropes are elements having?
Trả lời
(A)
different physical but the same chemical properties
20
A polymerization reaction is one in which?
Trả lời
(A)
small molecules form giant molecules
21
Which of the following is the electronic configuration of sodium?
(Atomic number of Na = 11)
Trả lời
(C)
1s2 2s22p6 3s1
22
In the reaction of oxygen with hydrogen to produce water, which of the following statements is true?
Trả lời
(E)
One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
23
Na2CO3 + 2HCI → 2NaCI + H2O + CO2. Using the above equation, what volume of carbondioxide, measured at s.t.p is liberated when 53g of sodium carbonate is dissolved in hydrochloric acid?
(1 mole of gas occupies 22.4 dm3 at s.t.p)
(Na = 23, C = 12, O = 16)
Trả lời
(B)
11.2 dm3
24
When sodium nitrate dissolves in water, ∆H is positive. This means that?
Trả lời
(D)
the reaction is endthermic
25
If an organic compound decolorizes bromine water then the compound is?
Trả lời
(C)
unsaturated
26
When air is compressed?
Trả lời
(D)
its temperature increases
27
Fats and oils are?
Trả lời
(C)
condensation products of long-chain fatty acids and glycerol
28
Which of the following statements about phosphorus is NOT correct?
Trả lời
(C)
Phosphorus exists in two allotropic forms
29
28.8 cm3 of nitrogen at 15°C is cooled to O°C at constant pressure, the new volume of nitrogen is?
Trả lời
(C)
27.3 cm3
30
If 48,000 coulombs of electricity are required to discharge 0.5 mole of sodium from a molten sodium chloride mass, then the number of coulombs required to discharge 2 moles of lead from molten lead (ll) chloride is?
Trả lời
(D)
384,000
31
The following compounds are given with their corresponding boiling points.
Compound Boiling Point
i.................................14°C
ii................................24°C
iii................................0°C
iv................................120°C
V.................................-2°C
From the above information, indicate which of the following is correct?
Trả lời
(D)
Three of the compounds are gaseous at 20 °C
32
The products of the reaction between dilute sulphuric acid and sodium thiosulphate crystals are?
Trả lời
(C)
Na2SO4 + SO2 + S + H2O
33
Which of the following is NOT a true statement of the kinetic Theory of Gases?
Trả lời
(D)
Every molecule has the same kinetic energy at a particular temperature
34
The electronic configuration of elements X and Y are X = 2, 8, 6; Y = 2, 8, 7. The bond in the compound formed by X and Y is expected to be?
Trả lời
(B)
covalent
35
5cm3 of a saturated solution of sodium chloride at 30°C gave, on careful evaporation, 1.95g of solid salt. The solubility of sodium chloride at 30°C?
(Na = 23, Cl = 35.5)
Trả lời
(D)
6.67 mole dm3
36
In the extraction of iron, which of the following reactions does NOT take place in the blast furnace?
Trả lời
(B)
2Fe2O3 + 3C → 4Fe + 3CO2
37
Pure sulfuric acid is a liquid of 1.84 density. What volume of it would be required to prepare 250 cm3 of 2.0 M solution?
(H = 1, S = 32, O = 16)
Trả lời
(B)
2.66
38
What mass of sodium carbonate solution is in 500 cm3 of 0.1 molar sodium carbonate solution?
(Na = 23, C = 12, O = 16)
Trả lời
(B)
5.3 g
39
Which of the following compounds and elements would sublime on exposure to the atmosphere?
Trả lời
(D)
Iodine
40
When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate?
Trả lời
(E)
only hydrogen sulphide deposits sulphur
41
Which one of the following metals is not normally extracted by chemical reduction because of its position in the electrochemical series?
Trả lời
(D)
Potassium
42
If one mole of aluminium contains 6 x 1023 atoms of aluminium, how many atoms are contained in 0.9g of aluminium?
(Al = 27)
Trả lời
(C)
2.0 x 1022
43
4g each of aluminium foil and aluminium powder were introduced respectively into flasks P and Q.
Flask P was treated with warm bench sodium hydroxide and all the aluminium dissolved in one hour. Flask Q was treated with cold sodium hydroxide and all the aluminium dissolved in 10 minutes. What was responsible for Q reacting faster than P?
Trả lời
(E)
Q has a greater surface area for the reaction than P
44
What happens when the nitrates of potassium, calcium, zinc and copper are separately heated?
Trả lời
(E)
The nitrates of calcium, zinc and copper decompose to their oxides
45
The scale formation in a kinetic used for boiling water is caused by the presence in water of?
