The atoms of four elements are represented as 20Q, 16R, 10S and 8T Which of the elements would be unreactive?
คำตอบ
(C)
S
2
Chlorine atom forms \(Cl^{-}\) by
คำตอบ
(D)
Gaining one electron
3
An element Z has a combining power of 3. Which of the following formulae is correct of its compounds?
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(C)
Z 2O 3
4
Electrovalent compounds are characterized by
คำตอบ
(C)
high melting point
5
The type of chemical bond that exists between potassium and oxygen in potassium oxide is
คำตอบ
(A)
ionic
6
Which of the following contains co-ordinate covalent bond?
คำตอบ
(C)
NH4
7
Elactrostatic force of attraction between sodium ion and halide ion is greatest in
คำตอบ
(C)
NaF
8
Which of the following non-metals reacts most readily with metals?
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(B)
Chlorine
9
A radioactive solid is best stored
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(D)
in a box lined with lead
10
What is the shape of a molecule of CCI4?
คำตอบ
(B)
Tetrahedral
11
What are the values of x and y in the following equation? \(^{234}_{90}\)Th → \(^y_x\)Pa + ß- particle
คำตอบ
(A)
91
234
12
Which of the following increases as boiling water changes to steam?
คำตอบ
(B)
degree of disorder in the system
13
9.60 g of a gas X occupies the same volume at 0.30 g of hydrogen under the same conditions. Calculate the molar mass of X [H = 1]
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(D)
64g mol -1
14
Which of the following gases is colourless, odourless and soluble in potassium hydroxide solution?
คำตอบ
(D)
CO2
15
The gas evolved when dilute tetraoxosulphate (VI) acid reacts with sodium hydrogen trioxocarbonate (IV) is
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(C)
carbon (IV) oxide
16
If a solution has a pH of 2, it can be concluded that it
คำตอบ
(D)
will produce effervescence with magnesium ribbon
17
Which of the following salts is stable to heat?
คำตอบ
(A)
K2CO3
18
Which of the following compounds dissolves in water to give an alkaline solution?
คำตอบ
(D)
Potassium oxide
19
Which of the following salts is an acid salt?
คำตอบ
(C)
KHSO4
20
What type of reaction is involved when wood shavings produce a brown gas with concentrated HNO3?
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(A)
Redox reaction
21
Chemical equilibrium is attained when
คำตอบ
(C)
concentrations of the reactants and products remain constant
22
What is the effect of using vanadium (V) oxide as catalyst in the reaction represented by the following equation? 2SO2 + O2 ⇌ 2SO3; ∆H = - xKJmol-1
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(D)
Reduces the time for attainment of equilibrium
23
A finely divided form of a metal burns more readily in air than the rod form because the rod has
คำตอบ
(B)
smaller surface area
24
Which of the following will displace copper from a solution of copper (ll) salt?
คำตอบ
(B)
Magnesium
25
What is the value of x in the following equation? Cr2O72- + 14H+ + xe- → 2Cr3+ + 7H2O
คำตอบ
(B)
6
26
In which of the following is the oxidation number of sulphur equal to -2?
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(B)
H2S
27
An iron nail placed in a solution copper (ll) tetraoxosulphate (VI) is soon covered with a deposit of copper. Which of the following equations represents the reactions ?
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(D)
Fe(s) + Cu2+ → Fe2+(aq) + Cu(s)
28
0.10 mol dm-3 NaCI conducts electricity better than 0.10 mol dm-3 CH3COOH because the solution of NaCI
คำตอบ
(A)
contains more ions
29
Which of the following occurs when a solution of CuSO4 is electrolysed using copper electrodes?
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(A)
The cathode becomes coated with copper
30
Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?
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(C)
Do a chromatogram of the colouring extract
31
2 moles of hydrogen gas will react completely with one mole of....
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(D)
CH≡C-CH2-CH3
32
C8H18 will undergo the following reactions except
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(D)
addition
33
Which of the following is correct about both compounds shown below? CH3CH 2CH2OH;CH 3
CH 2CH(OH)CH3
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(C)
Their general molecular formula is the same
34
Which of the following needs to be hydrolyzed before it shows reducing property?
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(C)
Sucrose
35
Two-organic substances are labelled K and L if K gave a blue-black colour with iodine solution and L gave a deep red precipitate with Million's reagent, it can be concluded that
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(A)
K is a carbohydrate and L is a protein
36
A colourless, odourless liquid T, gives effervescence with sodium trioxocarbonate (IV) and a white precipitate with silver trioxonitrate (V) solution T is most probably
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(D)
dilute hydrochloric acid
37
When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate formed re-dissolves in excess sodium hydroxide because
คำตอบ
(C)
zinc hydroxide is amphoteric
38
Which of the following on burning in air contributes to acid rain?
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(A)
Sulphur
39
If 20 cm3 of distilled water is added to 80 cm3 of 0.50 mol dm-3 hydrochloric acid, the concentration of the acid will change to
