The mass spectrometer can be used to measure mass of
คำตอบ
(A)
an atom
2
Find the number of neutrons in an atom represented by 4521X.
คำตอบ
(B)
24
3
The valence electrons in a chloride ion are [17CI]
คำตอบ
(B)
3s and 3p electrons only
4
What is the atomic number of an element whose cation Y+ has the electronic configuration 1s22s22p6?
คำตอบ
(C)
11
5
Atom \(^{234} _{88} Q\) decay by alpha emission to give an atom R. The atomic number and mass number of atom R are respectively
คำตอบ
(A)
86 and 230
6
Which of the following statements is not true of halogens?
คำตอบ
(C)
their ionic radii decrease down the group
7
Elements in the same group of the periodic table have
คำตอบ
(A)
the same number of valence electrons
8
Consider the following elements and their electronic configurations
W: 1s22s2
X: 1s 22s22p6
Y: 1s22s22p63s2
Z: 1s22s22p63s23p2. Which of the elements belong to the same group in the periodic table?
คำตอบ
(C)
W and Y only
9
Arrange the following elements in order of increasing electron affinity: Br2CI2
I 2
F 2
คำตอบ
(B)
I 2Br2CI2F 2
10
Water molecules are held together by
คำตอบ
(B)
hydrogen bond
11
The force of attraction between covalent molecules is?
คำตอบ
(A)
electrostatic attraction
12
What is the mass of 6.02 x 1024 atoms of magnesium? [Mg = 24, Avogadro constant = 6.02 x 1023 atoms mol-1]
คำตอบ
(A)
240g
13
Which of the following compounds with the corresponding masses contain the highest percentage of nitrogen? [N = 14]
คำตอบ
(A)
NH3 = 17
14
Which of the following compounds with the corresponding masses contain the highest percentage of nitrogen? [N = 14]
คำตอบ
(A)
NH3 = 17
15
If 5.00cm3 of 0.20 mol dm-3Na2CO3 was diluted with distilled water to obtain 250 cm3 solution, what is the concentration of the resulting solution?
คำตอบ
(A)
0.004 mol dm-3
16
Consider the reaction represented by the following equation: Zn(s) + 2HCI(aq) → ZnCI2(aq) + H2(g) what volume of hydrogen gas is produced at s.t.p. when 3.25 g of zinc reacts with excess dilute HCI? [Zn = 65, Molar gas volume at s.t.p. = 22.4 dm-3]
คำตอบ
(A)
1.12 dm3
17
Which of the following gases has the lowerst rate of diffusion under the same conditions of temperature and pressure? [H = 1, O = 16, Ne = 20, CI = 35]
คำตอบ
(A)
Chlorine
18
In a fixed volume of a gas, an increase in temperature results in an increase in pressure due to an increase in the
คำตอบ
(A)
number of the collisions between the gas molecules and the walls of the container
19
When concentrated \(H_2SO_4\) is added to NaCI (s), the gas evolved
คำตอบ
(B)
forms a white preciptate with AgNO3(aq)
20
The collision theory proposes that
คำตอบ
(C)
reactants must collide with a certain minimum amount of energy to from products
21
Diamond does not conduct electricity because it?
คำตอบ
(A)
has no free valence electrons
22
Which of the following set of equations could be used to represent the standard enthalpy of formation of glucose?
คำตอบ
(B)
6CO2(g) + 6H2O (l) → C6H12O6(s) + 6O 2(g)
23
The colour of phenolphthalein indicator in dilute HNO is
คำตอบ
(A)
colourless
24
An aqueous solution of CaCI2 is
คำตอบ
(D)
a neutral solution
25
Which of the following compounds would dissolved in water to give a solution whose pH is less than 7?
คำตอบ
(A)
AI(NO3)3
26
Consider the reaction represented by the question below: KOH(aq) + HCI(aq) → KCI(aq) + H2O(l) What volume of 0.25 mol dm-3 KOH would be required to completely neutralize 40 cm3 of 0.10 mol dm -3 HCI?
คำตอบ
(D)
16cm3
27
When 100 cm3 of a saturated solution of KCIO3 at 40oC is evaporated, 14 g of the salt is recovered what is the solubility of KCIO3 at 40oC? [KCIO3 = 122.5]
คำตอบ
(C)
1. 14 mol dm-3
28
The high solubility of ethanol in water is due to its
คำตอบ
(D)
hydrogen bonding
29
Consider the equilibrium reaction represented by the equation: 2SO2(g) + O2(g) ⇌ 2SO3(g) ∆H = - 197 kJmol-1. At equilibrium, increase in the total pressure of the system brings about
คำตอบ
(C)
increase in temperature of SO3
30
In dry Leclanche cell, manganese (IV) oxide acts as
คำตอบ
(D)
depolarizer
31
Oxidation takes place at the anode during electrolysis because the anode
คำตอบ
(C)
has excess electrons
32
Calculate the quantity of electricity passed when 0.4 A flows for 1 hour 20 minutes through an electrolytic cell
คำตอบ
(C)
1920 C
33
A mixture of kerosene and diesel oil can be separated by
คำตอบ
(B)
distillation
34
Which of the following compounds would not give a precipitate with ammoniacal AgNO3 solution?
คำตอบ
(A)
CH3 C≡CCH3
35
When ethanol is heated with excess concentrated tetraoxosulphate (VI) acid, the organic product formed is
คำตอบ
(D)
ethene
36
The hydrolysis of groundnut oil by potassium hydroxide is known as
คำตอบ
(B)
saponification
37
What is the main type of reaction alkenes undergo?
คำตอบ
(A)
Addition
38
Arrange the following compounds in order of increasing boiling point
l.CH\(_3\)CH\(_2\)CH\(_2\)OH
II.CH\(_3\)CH\(_2\)OH
III.CH\(_3\)CH\(_2\)CH\(_2\)CH\(_2\)OH
IV.CH\(_3\)CH\(_2\)CH\(_2\)CH\(_2\)CH\(_3\)
คำตอบ
(D)
IV < II < I< III
39
A hydrocarbon containing 88.9% carbon has the empirical formula [H = 1 C = 12]
คำตอบ
(B)
CH2
40
A solution of a salt was acidified with HCI when a few drops of BaCI2 solution were added, a white precipitate was formed. Which of the following anions is present in the salt?
