A mixture of sugar and sulphur can be separated by?
คำตอบ
(C)
dissolution in water, filtration and evaporation
2
Which of the following is a physical change?
คำตอบ
(A)
Freezing ice cream
3
The percentage of water of crystallization in ZnSO\(_4\).7H\(_2\)O is?
[Zn = 65, S = 32, O = 16, H = 1]
คำตอบ
(B)
44%
4
0.0075 mole of calcium trioxocarbonate (IV) is added to 0.015 mole of a solution of hydrochloric acid. The volume of gas evolved at s.t.p is?
[Molar volume of a gas at s.t.p = 22.4 dm3]
คำตอบ
(B)
168cm3
5
A gas exerts pressure on its container because?
คำตอบ
(A)
the molecules of a gas collide with the walls of the container
6
The basic assumption in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that the?
คำตอบ
(C)
gaseous molecules will continue their motion indefinitely
7
If an atom is represented as \( _{11}^{23}X \), which of the following deduction is correct?
คำตอบ
(D)
it is an alkali metal
8
Cathode rays causes an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays?
คำตอบ
(D)
travel in straight lines
9
Which quantum number divides shells into orbitals?
คำตอบ
(B)
Arzimuthal
10
The type of bonding in \({Cu(NH_3)_4}^2\)+ is?
คำตอบ
(A)
coordinate covalent
11
The mixture of gases used in a photographer's flash tube is?
คำตอบ
(B)
krypton and xenon
12
When sodium trioxocarbonate (IV) decahydrate loses its water of crystallization to the atmosphere, the process is?
คำตอบ
(B)
efflorescence
13
Water can be obtained as the only product during the?
คำตอบ
(C)
combustion of hydrogen
14
If 10.5g of lead (II) trioxonitrate (V) is dissolved in 20cm3 of distilled water at 18oC, the solubility of the solute in mol dm-3 is
[Pb = 207, N = 14, O = 16]
คำตอบ
(A)
1.60
15
For a given solute, the concentration of its saturated solution in different solvents are
คำตอบ
(B)
different at the same temperature
16
The major source of oxides of nitrogen is from the burning of
คำตอบ
(C)
fuel
17
The acid used in electrolysis of water is dilute?
คำตอบ
(C)
H2SO4
18
What volume of 1.5M solution of KOH would contain 0.045 moles
คำตอบ
(B)
30.00 cm3
19
The salt formed from a reaction between citric acid and sodium hydroxide in solution will be?
คำตอบ
(B)
basic
20
The colour changes observed when testing for reducing agents using acidified potassium heptaoxodichromate (VI) solution is?
คำตอบ
(B)
orange to green
21
The oxidation state of Cr in K\(_2\)Cr\(_2\)O\(_7\) is?
คำตอบ
(B)
+6
22
Which of the following metals is purified commercially by electrolysis?
คำตอบ
(D)
Cu
23
What current will deposit 3.25g of zinc in 2hrs?
[Zn = 65, F = 96500 mol-]
คำตอบ
(C)
1.34A
24
C(s) + H2O(g) → H2(g) + CO2(g)
ΔG for the reaction above at 1300k is -43KJ. At this temperature, the reaction is?
คำตอบ
(C)
feasible
25
Two equal bulbs, one containing ammonia and the other nitrogen are opened mouth - to - mouth to each other at room temperature. The entropy in the mixture of gases is likely to?
คำตอบ
(B)
increase
26
In the diagram above, which of the curves represents the evolution of oxygen with time in the equation 2KClO3(s) → 2KCl(s) + 3O2(g)?
คำตอบ
(D)
R
27
A catalyst increase the rate of a chemical reaction by providing a path that?
คำตอบ
(C)
lowers the activation energy
28
CuO(s) + H\(_2\)(g) ↔ Cu(s) + H\(_2\)O(g)
What is the effect of increasing the pressure on the equilibrium reaction above?
คำตอบ
(C)
There is no effect
29
The equilibrium of an endothermic reaction which proceeds with an increase in volume can be shifted in the reverse direction by
คำตอบ
(C)
decreasing the temperature and increasing the pressure
30
The oxidation of ammonia in excess air produces?
คำตอบ
(A)
NO
31
Hydrogen sulphide gas can act as?
คำตอบ
(D)
a precipitating agent
32
The gasification of coke is used for the manufacturing of?
คำตอบ
(C)
synthetic gas
33
The gas that is most useful in protecting humans against solar radiation is?
คำตอบ
(B)
ozone
34
Which of the following allotrope of carbon is a constituent of a lead pencil?
คำตอบ
(A)
Graphite
35
which of the following metals will show the highest metallic character?
คำตอบ
(C)
Barium
36
Copper metal dissolves in concentrated trioxonitrate (V) acid with the resultant evolution of?
คำตอบ
(C)
NO2
37
The type of iron that is best suited for welding, making nails, chains and iron rods is?
คำตอบ
(B)
wrought iron
38
In the electrolytic extraction of aluminum, the function of the molten cryolite is to
คำตอบ
(B)
lower the melting point of aluminium oxide
39
One of the products of the thermal decomposition of sodium trioxonitrate (V) is?
คำตอบ
(C)
sodium dioxonitrate (III)
40
A cracking process in petroleum refining can be represented by
คำตอบ
(C)
heptane to propene and butane
41
Which of the following molecules has two other positional isomers?
คำตอบ
(D)
CH2CHBrCH2Br
42
Which of the following class of compounds can exist as dipolar ions in solution?
คำตอบ
(D)
Amino acids
43
Lucas reagent is used to test for?
คำตอบ
(C)
alkanols
44
A compound commonly used for sterilization and preservation of specimens and food is
คำตอบ
(A)
ethanol
45
An organic compound reacted with bromine water to give a colourless solution. The compound is probably an?
