The phenomenon observed when dust particles collide randomly in a beam of sunlight is known as?
คำตอบ
(A)
Tyndal effect
2
The mass number of an element is the sum of its
คำตอบ
(C)
protons and neutrons
3
How many unpaired electrons are there in an atom of an element with the following electronic configuration? 1s22s22p6
คำตอบ
(A)
o
4
Radon is used as a tracer in medical research because it
คำตอบ
(B)
is radioactive
5
What is the most probable group of an element which is a soft, silvery white solid and reacts violently with water?
คำตอบ
(B)
Group 1
6
In linear molecules, the bond angle is
คำตอบ
(E)
180o
7
A sodium atom and a sodium ion have the same
คำตอบ
(A)
number of neutrons
8
If the atomic number of an element X is 11 and that of nitrogen is 7, the most likely formula of the nitride of X is
คำตอบ
(A)
X3N
9
An increase in the pressure of a gas results in a decrease in its
คำตอบ
(C)
volume
10
A given volume of methane diffuses in 20 seconds. How long will it take the same volume of sulphur (IV) oxide to diffuse under the same conditions? [CH\(_4\) = 16; SO\(_2\) = 64]
คำตอบ
(C)
40 seconds
11
An acid is a substance which in the presence of water produces
คำตอบ
(D)
hydroxonium ions
12
Which of the following is a general method of preparing acids?
คำตอบ
(C)
Reaction between an anhydride and water
13
Which of the following is a general method of preparing acids?
คำตอบ
(D)
Reaction between an anhydride and water
14
The loss of molecules of water of crystallization to the atmosphere by some crystalline salts is known as
คำตอบ
(A)
efflorescence
15
Which of the following ions will migrate to the cathode during electrolysis?
คำตอบ
(A)
Zinc ions
16
What quantity of electrons (in mole) is lost when one mole of iron (ll) ions is oxidized to iron (lll) ions?
คำตอบ
(E)
1 mole
17
The common feature of reactions at the anode is that
คำตอบ
(B)
oxidation is involved
18
From the following equations, what is the order of decreasing reactivity of X, Y and Z? Y (s) + X2+(aq) → Y2+(aq) + X(s) X(s) + Z2+(aq) → X2+(aq) + Z(s)
คำตอบ
(B)
Y > X > Z
19
What is the value of x in the following equation? MnO- 4 + 4H+ + xe- → MnO 2 + 2H2O
คำตอบ
(B)
3
20
If the value of ∆H for a reaction is negative, it means that the reaction is
คำตอบ
(B)
exothermic
21
How much heat will be liberated if 8g of hydrogen burns in excess oxygen according to the following equation? 2H2 + O2→ 2H2O,∆H = -571.7KJ (H = 1)
คำตอบ
(C)
1143.4KJ
22
The position of equilibrium in a reversible reaction is affected by
คำตอบ
(B)
change in concentration of the reactants
23
Separation of mixture of solids by physical methods can be based on differences in the following except
คำตอบ
(D)
molar mass
24
Ethene undergoes mainly addition reactions because it is
คำตอบ
(C)
unsaturated
25
The reaction between alkanoic acids and alkanols in the presence of a mineral acid is known as
คำตอบ
(D)
esterification
26
Which of the following is the relative molecular mass of a compound which has empirical formula CH\(_2\)O? (H = 1; C = 12; O = 16)
คำตอบ
(D)
180
27
The by-product of the fermentation of sugar to ethanol is
คำตอบ
(E)
carbon (lV) oxide
28
Alkanes react with the halogens mainly by
คำตอบ
(E)
substitution
29
Which of the following is used widely in the manufacture of flavours and perfumes?
คำตอบ
(A)
Alkanoates
30
The use of diamond in abrasives is due ti its
คำตอบ
(D)
hardness
31
Which of the substance lettered P to V in the equation below would be left on the filter paper if the reaction mixture were filtered? P (aq) + Q(aq) → V(s) + R(aq) + T(g)
คำตอบ
(C)
V
32
When chlorine is added to slaked lime, the product obtained is
คำตอบ
(A)
bleaching powder
33
Which of the following when heated strongly in air will leave a metal as residue?
คำตอบ
(C)
Silver trioxonitrate (V)
34
Which of the following is used as water softener?
คำตอบ
(A)
Na2CO3.10H2O
35
The following oxides react with both acids and bases to form salts except
คำตอบ
(E)
carbon (Iv) oxide
36
Which of the following metals is not extracted by electrolysis ?
คำตอบ
(A)
lron
37
Which of the following is an ore of aluminium?
คำตอบ
(D)
Bauxite
38
Lead and tin are the components of
คำตอบ
(E)
soft solder
39
An atom 17 protons, 17 electrons and 18 neutrons has a mass number of
คำตอบ
(D)
35
40
If an element R belongs to the same group as sodium, an aqueous solution of ROH will
คำตอบ
(D)
have pH greater than 7
41
Element X, with electronic configuration 2, 8, 2 and element Y with electronic configuration 2, 8, 7 are like to combine by
คำตอบ
(C)
electrovalent bonding
42
The valence electrons of element 12Mg are in the
คำตอบ
(E)
3s orbital
43
Which of the following statements is correct about sodium chloride in the solid state?
คำตอบ
(A)
it exists as aggregates of ions
44
Which of the following Group 1 elements has the highest ionization energy?
