Which of the following atoms contains the highest number of electrons in the outermost shell?
คำตอบ
(B)
10Ne
2
What is the electronic configuration of an element represented as 199X?
คำตอบ
(A)
1s 22s2 2p 5
3
Pauli Exclusion Principle is related to
คำตอบ
(A)
quantum numbers of electrons
4
Which of the orbitals 4s, 4p, 4d and 4f has the lowest energy?
คำตอบ
(D)
4s
5
Two radioactive elements Q and S have half-life periods of 10 hours and 20 hours respectively. Therefore
คำตอบ
(D)
S is more stable than Q
6
Calcium atom ionizes by
คำตอบ
(B)
losing two electrons
7
Which of the following properties increases down a group in the Periodic Table?
คำตอบ
(A)
Atomic radius
8
In the Periodic Table, the elements that loss electrons most readily belong to
คำตอบ
(A)
Group 1 A
9
Which of the following reactions is not feasible?
คำตอบ
(B)
Cl2 + 2NaF → 2NaCI + F2
10
Which of the following halogens is the most reactive?
คำตอบ
(A)
F2
11
The crystal layers in graphite are held together by
คำตอบ
(B)
van der Waals' forces
12
Which of the following compounds has the highest ionic character?
คำตอบ
(D)
KCI
13
If an element with high electron affinity combines with another element with low ionization energy the bond formed will be mainly
คำตอบ
(B)
ionic
14
One mole of a compound M(HCO3)2 has a mass of 162g. Calculate the relative atomic mass of M. [H = 1, C =12, O = 16]
คำตอบ
(D)
40
15
Exhaust fumes discharged from a smoky vehicle gradually become invisible as a result of
คำตอบ
(A)
diffusion
16
Which of the following movements can be described as random motion?
คำตอบ
(C)
Gas molecules colliding in a flask
17
Equal volumes of CO2 cnd CO at s.t.p have the same
คำตอบ
(D)
number of molecules
18
Gas molecules are said to be perfectly elastic because
คำตอบ
(A)
they collide without loss of energy
19
What volume of hydrogen is produced at s.t.p. When 2.60 g of zinc reacts with excess HCI according to the following equation? Zn(s) + 2HCI(aq) → ZnCI 2(aq) + H2(g) [Zn = 65; 1 mole of a gas occupies 22.4dm3 at s.t.p]
คำตอบ
(B)
0.896dm 3
20
Helium is preferred to hydrogen in filling balloons because hydrogen
คำตอบ
(A)
is inflammable
21
30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen to form steam according to the following equation 2H2(g) + O2(g) → 2H2O(g).
Calculate the total volume of the gaseous mixture at the end of the reaction
คำตอบ
(B)
35cm3
22
An exothermic reaction is one which involves
คำตอบ
(B)
loss of heat to the surrounding
23
Which of the following is an acid salt?
คำตอบ
(D)
NaHCO3
24
Which of the following compounds dissolves in water to form a solution with pH below 7?
คำตอบ
(C)
Ammonium chloride
25
If the solubility of KHCO3 is 0.40 mole dm-3 at room temperature , calculate the mass of KHCO3 in 100dm3 of the solution at this temperature. [KHCO3 = 100hmol]
คำตอบ
(A)
4.0g
26
The property of calcium chloride which makes it useful as a drying agent is that it is
คำตอบ
(B)
deliquescent
27
Which of the following lowers the activation energy of a chemical reaction?
คำตอบ
(D)
Catalyst
28
Consider the reaction represented by the following equation: H2(g) + 12(g) → 2HI(g). The number of effective collisions of molecules of the reactants decreases as
คำตอบ
(C)
the volume of the system is increased
29
What will be the effect of increase in pressure on the following system at equilibrium? 2NH2(g) N2(g) + 3H2(g)
คำตอบ
(C)
the concentration of ammonia will increase
30
Which of the following is not correct about oxidation number convention? The oxidation number of a/an
คำตอบ
(D)
atom of a diatomic molecules is + 2
31
Equal volumes of water were added to one mole of each of the following compounds. Which of them produced the largest number of ions
คำตอบ
(B)
Sodium trioxonitrate (V)
32
When dilute copper (ll) chloride solution is electrolysed, the reaction at the cathode is represented by the equation
คำตอบ
(B)
Cu2+ + 2e- → Cu
33
How many carbon atoms are present in one molecule of 2-methylpropane?
คำตอบ
(C)
4
34
Which of the following is the most reactive towards bromine?
คำตอบ
(C)
Ethyne
35
Which of the following compounds is unsaturated?
คำตอบ
(C)
Methylbenzene
36
Which of the following compounds reacts with sodium hydroxide to form a salt?
คำตอบ
(A)
CH 3CH 2COOH
37
Alkanoates are produced from alkanols by
คำตอบ
(D)
esterification
38
Which of the following is a secondary alkanol?
คำตอบ
(C)
CH 3-CH(OH)-CH 3
39
Geometric (cis-trans) isomerism is exhibited by
คำตอบ
(A)
C 2H 2CI 2
40
Which of the following is needed to produce slag during the extraction of iron in the blast furnace?
