An element X has 127 neutrons and 82 electrons.
Its atomic number is?
คำตอบ
(D)
82
2
When a bottle of Coca-Cola is opened, bubbles of evolve. The gas is?
คำตอบ
(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?
คำตอบ
(E)
carbondioxide
4
An example of a strong electrolyte is?
คำตอบ
(D)
sodium formate
5
The oxidation number of manganese in KMnO4 is?
คำตอบ
(D)
+7
6
Methane is member of the homologous series called?
คำตอบ
(D)
alkanes
7
For iron to rust, there should be present?
คำตอบ
(D)
oxygen and moisture
8
The mass number of an atom is?
คำตอบ
(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?
คำตอบ
(D)
both have identical electronic configuration
10
Oxidation is the process of?
คำตอบ
(B)
loss of electrons
11
the number of atoms in one mole of a substance is equal to?
คำตอบ
(B)
the avogadro number
12
Which of the following statements is NOT true of electrovalent compounds?
คำตอบ
(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 ?
คำตอบ
(C)
a dehydrated agent
14
In the reaction
C + 2HNO3 → CO2 + NO2 + NO + H2O nitric acid is acting as?
คำตอบ
(C)
an oxidizing agent
15
The brown coloration in nitric acid prepared in the laboratory can be removed by?
คำตอบ
(B)
bubbling air through the acid
16
Which of the following processes takes place during electrolysis?
คำตอบ
(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?
คำตอบ
(A)
CaO
18
Which of the following can have an isomer?
คำตอบ
(B)
C4H10
19
Allotropes are elements having?
คำตอบ
(A)
different physical but the same chemical properties
20
A polymerization reaction is one in which?
คำตอบ
(A)
small molecules form giant molecules
21
Which of the following is the electronic configuration of sodium?
(Atomic number of Na = 11)
คำตอบ
(C)
1s2 2s22p6 3s1
22
In the reaction of oxygen with hydrogen to produce water, which of the following statements is true?
คำตอบ
(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)
คำตอบ
(B)
11.2 dm3
24
When sodium nitrate dissolves in water, ∆H is positive. This means that?
คำตอบ
(D)
the reaction is endthermic
25
If an organic compound decolorizes bromine water then the compound is?
คำตอบ
(C)
unsaturated
26
When air is compressed?
คำตอบ
(D)
its temperature increases
27
Fats and oils are?
คำตอบ
(C)
condensation products of long-chain fatty acids and glycerol
28
Which of the following statements about phosphorus is NOT correct?
คำตอบ
(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?
คำตอบ
(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?
คำตอบ
(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?
คำตอบ
(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?
คำตอบ
(C)
Na2SO4 + SO2 + S + H2O
33
Which of the following is NOT a true statement of the kinetic Theory of Gases?
คำตอบ
(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?
คำตอบ
(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)
คำตอบ
(D)
6.67 mole dm3
36
In the extraction of iron, which of the following reactions does NOT take place in the blast furnace?
คำตอบ
(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)
คำตอบ
(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)
คำตอบ
(B)
5.3 g
39
Which of the following compounds and elements would sublime on exposure to the atmosphere?
คำตอบ
(D)
Iodine
40
When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate?
คำตอบ
(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?
คำตอบ
(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)
คำตอบ
(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?
คำตอบ
(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?
คำตอบ
(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?
