A mixture of sand, ammonium chloride and sodium chloride is best separated by?
คำตอบ
(A)
sublimation followed by addition of water and filteration
2
A pure solid usually melts?
คำตอบ
(B)
over a narrow range of temperature
3
At the same temperature and pressure, 50 cm3 of nitrogen gas contains the same number of molecules as?
คำตอบ
(C)
50 cm3 of ammonia
4
8g CH4 occupies 11.2 dm3 at s.t.p. What volume would 22 g of CH3CH2CH3 occupy under the same condition?
(C = 12, H = 1)
คำตอบ
(B)
11.2 dm3
5
To what temperature must a gas 273 K be heated in order to double both its volume and pressure?
คำตอบ
(D)
1092 K
6
For a gas, the relative molecular mass is equal to 2Y. What is Y?
คำตอบ
(B)
The vapour density of the gas
7
The densities of two gases, X and Y, are 0.5 g dm-3 and 2.0 dm-3 respectively.
What is the rate of diffusion of X relative to Y?
คำตอบ
(C)
2.0
8
The shape of ammonia molecule is?
คำตอบ
(A)
trigonal planar
9
An increase in temperature causes an increase in the pressure of a gas because?
คำตอบ
(B)
the molecules of the gas bombard the walls of the container more frequently
10
The number of electrons in the valence shell of an element of atomic number 14 is?
คำตอบ
(D)
4
11
Which of the following physical properties decreases down a group in the periodic table?
คำตอบ
(D)
Electronegativity
12
Element X, Y and Z belong to a groups I, V and VII respectively. Which of the following is TRUE about the bond types of XZ and YZ3?
คำตอบ
(C)
XZ is electrovalent and YZ3 is covalent
13
A solid that absorbs water from he atmosphere and forms an aqueous solution is?
คำตอบ
(C)
deliquescent
14
A major effect of oil pollution in coastal waters is the?
คำตอบ
(A)
destruction of marine life
15
Sodium chloride has no solubility product value because of its?
คำตอบ
(B)
high solubility
16
The solubility, in moles per dm3 of 20.2 g of potassium trioxonitrate (V) dissolve in 100 g of the resulting mixture is?
(K = 39, O = 16, N =14).
คำตอบ
(D)
2.00
17
Which of the following atoms represents deuterium?
คำตอบ
(C)
No protons = 1, No of neutrons = 1, No of electrons = 1
18
A few drops of concentrated HCI are added to about 10cm3 of a solution of pH 3.4. The pH of the resulting mixtures is?
คำตอบ
(A)
less than 3.4
19
Which of the following compounds is a base?
คำตอบ
(B)
CaO
20
20 cm\(^3\) of a 2.0 M solution of ethanoic acid was added to excess of 0.05 M sodium hydroxide. The mass of the salt produced is?
(Na = 23, C = 12, O = 16, H = 1)
คำตอบ
(C)
3.28 g
21
What volume of Oxygen measured at s.t.p would be liberated on electrolysis by 9650 coulombs of electricity?
(Molar volume of gas = 22.4 dm\(^3\), 1F = 96,500 C/mol)
คำตอบ
(D)
0.560 dm3
22
Crude copper could be purified by the electrolysis of concentrated copper (II) chloride if the crude copper is?
คำตอบ
(C)
made the anode
23
H- + H2(I)O → H2(g) + OH-(aq). From the equation above, it can be inferred that the?
คำตอบ
(B)
hydride ion is a reducing agent
24
An anhydride is an oxide of non-mental
คำตอบ
(C)
whose solution in water has a pH less than 7
25
MnO4(aq) + 8H + (aq) + 5Fe2+ → Mn2+(aq) + 4H2O(I). The oxidation number of manganese in the above reaction changed from?
คำตอบ
(A)
+7 to +2
26
Which of the following is TRUE of Le Chatelier's Principle for an exothermic reaction?
คำตอบ
(B)
Increase in temperature will cause a decrease in the equilibrium constant
27
Which of the following are produced when ammonium trioxonitrate (V) crystals are cautiously heated in a hard glass round bottomed flask?
คำตอบ
(A)
N2O and steam
28
Which of these metals CANNOT replace hydrogen from alkaline solutions?
คำตอบ
(D)
Iron
29
Clothes should be properly rinsed with water after bleaching because?
คำตอบ
(D)
hydrogen chloride solution is produced during bleaching
30
Which of these solutions will give a white precipitate with a solution of barium chloride acidified with hydrochloric acid?
คำตอบ
(B)
Sodium tetraoxosulphate (IV)
31
SO3 is NOT directly dissolved in water in the preparation of H2SO4 by the contact process because?
คำตอบ
(A)
the reaction between SO3 and water is violently exothermic
32
In an electrolytic set-up to protect iron from corrosion, the iron is?
คำตอบ
(A)
made cathode
33
Which of the following is NOT true of metals?
คำตอบ
(C)
Their oxides are acidic
34
Which of the following is the correct order of decreasing activity of the metals Fe, Ca, Al and Na?
คำตอบ
(B)
Na> Ca> Al> Fe
35
Which of the following compounds is NOT an isomers of 2,2 dimethylbutane?
คำตอบ
(A)
2-methylbutane
36
When sodium is added to ethanol, the products are?
คำตอบ
(D)
sodium ethoxide and hydrogen
37
The general formula of alkanoates is?
คำตอบ
(D)
RCOOR
38
One mole of a hydrocarbon contains 48 g of carbon. If it vapour density is 28, the hydrocarbon is?
คำตอบ
(B)
an alkene
39
Which of the following reagents will confirm the presence of unsaturation in a compound?
คำตอบ
(B)
Bromine water
40
The diagram above represents an atom of
คำตอบ
(A)
magnesium
41
The set-up above would be useful for determining the amount of
คำตอบ
(B)
water vapour in air
42
The ∆H for the reaction represented by the energy profile above is
คำตอบ
(D)
-50 kJ mol-1
43
In the diagram above the activation energy is represented by
คำตอบ
(A)
y - x
44
2HCL(ag) + CaCO3(ag) → CaCL2(ag) + H2O(1) + CO from the reaction above, which of the following curves represents the consumption of calcium trioxocarbonate (IV) as dilute HCL is added to it?
คำตอบ
(D)
P
45
In the diagram above, R is a mixture of?
คำตอบ
(C)
potassium tetratoxomanganate (VII) and concentrated HCI
46
The IUPAC name of the compound above is
คำตอบ
(C)
3,3-dimethyl but -1-ene
47
Use the diagram above to answer this question. The reaction taking place in flask G is known as?
คำตอบ
(C)
dehydration
48
MnO4(aq) + 8H + 5Fe2+ \(\to\) Mn2+(aq) + 5Fe3+(aq) + H2O. The oxidation number of maganese in the above reaction changed from
คำตอบ
(A)
+7 to +2
49
which of these metals CANNOT replace hydrogen from alkaline solutions?
คำตอบ
(D)
Iron
50
Clothes should be properly rinsed with water after bleaching because
คำตอบ
(D)
hydrogen chloride solution is produced during bleaching
