Which of the following statements is correct during the electrolysis of a caustic soda solution using platinum electrodes?
คำตอบ
(E)
AAlkalinity at the cathode increases
3
An amphoteric oxide is an?
คำตอบ
(D)
oxide that behaves both as a base as well as an acid
4
Water is poured over a white solid and a colourless neutral gas is evolved which burns with a sooty flame. The white solid is?
คำตอบ
(C)
calcium carbide
5
Cotton is almost pure?
คำตอบ
(D)
celluose
6
Which of the following types of reactions takes place between C2H6 and the halogens?
คำตอบ
(A)
Substitution
7
The product formed at the the cathode during the electrolysis of sodium chloride solution with carbon electrodes is?
คำตอบ
(C)
hydrogen
8
Sodium carbonate crystals on exposure to a dry atmosphere change to a white powder. This phenomenon is known as?
คำตอบ
(D)
efforescence
9
Which of the following statements is incorrect?
คำตอบ
(E)
Copper reacts with steam
10
In the reaction NH3 + H+ → NH4+, the bond formed results from?
คำตอบ
(B)
an electron pair donated by NH3
11
Which of the following CANNOT be obtained by fractional distillation of petroleum?
คำตอบ
(E)
Hydrogen
12
In the reaction N2(g) + O(g)
↔ 2NO(g) produced i an increase in the total pressure will?
คำตอบ
(E)
have no effect
13
In the chemical reaction A + B \(\to\) C + D, more of D is formed?
คำตอบ
(E)
if D is continuously removed from the reaction mixture
14
1.00 g of the oxide of metal X (atomic mass = 64) gave 0.80 g of the metal when reduced with hydrogen.
The formula of the oxide is?
คำตอบ
(B)
XO
15
When a solution of silver (l) nitrate is saturated with hydrogen sulphide, a black precipitate forms which is?
คำตอบ
(B)
Ag2S
16
The production of ammonia by the haber process may be represented by the equilibrium equation N2(g) + 3H2(g) ↔ 2NH3 ∆H = -22KJ. Therefore the production of ammonia will be favoured by?
คำตอบ
(D)
a combination of low temperature and high pressure
17
Which of the following represents ethyl ethanonate?
คำตอบ
(D)
CH3CO2CH2CH3
18
Which of the following equations represents an oxidizing action of sulphur dioxide?
คำตอบ
(D)
SO2 + 2H2S → 3S + 2H2O
19
If the rate of diffusion of oxygen gas is taken as 1, what will be rated of diffusion of methane whose relative molar mass is 16?
คำตอบ
(C)
1.4
20
If the temperature of a gas is increased?
คำตอบ
(C)
the gas will occupy a greater volume if the pressure is constant
21
When a little brine was added to a metal nitrate a white precipitate was formed which first turned violet and then black on exposure to ai. The metal nitrate is therefore?
คำตอบ
(D)
silver nitrate
22
If atom X with six electrons in its outermost shell combines with atom Y with one electron in its outermost shell to form an ionic compound, then?
คำตอบ
(C)
one atom of X will combine with two of Y
23
The nitrogen gas obtained by burning an excess of phosphorus in air has a density higher than the nitrogen from nitrogen compounds because the nitrogen from air is contaminated with?
คำตอบ
(D)
rare gases
24
When air is passed through alkaline pyrogallol and then over quicklime, the only gases left are?
คำตอบ
(D)
nitrogen and the rare gases
25
9.8g of solid potassium chlorate (KCIO3) were added to 40 cm3 of water and heated to dissolve all the solid. As he solution cooled, crystals of potassium chlorate started forming at 60°C. The solubility of potassium chlorate at 66°C is therefore?
คำตอบ
(E)
2.0 mole per dm3
26
100 cm3 of oxygen is made to react with 50 cm 3 of hydrogen, and the whole reaction mixture was then passed through anhydrous calcium chloride. What is the volume of gas left?
คำตอบ
(D)
75 cm3
27
A mixture contains 20cm3 of hydrogen, 35cm3 of oxygen, 15cm3 of carbon monoxide and 10cm3 of nitrogen at S.T.P. Which of the following gives the mole fraction of hydrogen in this mixture?
คำตอบ
(D)
0.25
28
0.07g of a hydride of carbon occupies 56.0cm\(^3\) at S.T.P. When vaporized and contains 14.29% by mass of hydrogen. The formula of the hydrocarbon is(C = 12, H = 1)
คำตอบ
(C)
C2H4
29
The pressure on 100 cm3 of oxygen gas at 35°C is 750mm of Hg.What would be the volume of the gas if the pressure is increased to 1000mm of Hg without changing the temperature?
คำตอบ
(C)
75 cm3
30
Which of the following bonds exist in crystalline ammonium chloride (NH4Cl)?
คำตอบ
(C)
Ionic covalent and co-ordinate
31
When a pressure cooker is half filled with water, and heated to boiling point, then the pressure inside the cooker will?
คำตอบ
(E)
increase, because the water vapour molecules now strike the walls of the tube more frequently because of their increased velocity
32
An element X has two isotopes, \(^{20} _{10}X\) and \(^{22} _{10}X\),
present in the ratio 1:3. The relative atomic mass of X would be?
คำตอบ
(C)
21.5
33
Which of the following is a neutralization reaction? Addition of
คำตอบ
(D)
nitric acid to sodium hydroxide
34
A current of 10.0A was passed for 1 hour through a solution of copper (ll) sulphate between the copper electrodes. Which of the following observation would be correct?
(1 Faraday = 96,500 coulombs) (i) 0.186 mole of copper is dissolved from the anode. (ii) 0.372 mole of copper is deposited on the cathode. (iii) the original Cu2+ ion concentration of the solution remains unchanged. (iv) the original Cu2+ ion concentration of the solution decreases.
คำตอบ
(C)
i and iv
35
In the preparation of carbon monoxide by heating ethanedioic acid with concentrated sulphuric acid, the concentrated sulphuric acid act as?
คำตอบ
(C)
a dehydrating agent
36
When copper powder is heated with concentrated sulphuric acid, the gas produced is?
คำตอบ
(B)
sulphur dioxide
37
Magnesium ribbon was added to each of the following aqueous solution in turn: H2SO4, AgNO3, HNO3, HCl, NH3, HCl, NH3. In which case does the magnesium become covered with a dark precipitate?
คำตอบ
(B)
AgNO3
38
How many grams of methylacetylene (propyne) CH\(_3\) — C Ξ CH will completely discharge the colour of 8g of bromine?
(Br = 80, C = 12, H = 1)
คำตอบ
(B)
1.0
39
What weight of sodium hydroxide is required to make 500 cm\(^3\) of 0.2 M solution?
(Na = 23, O = 16, H = 1)
คำตอบ
(D)
4 g
40
Which of the following combinations of conditions may increase the rate of a chemical reaction?
คำตอบ
(C)
Increase in temperature, increase in concentration, addition of a catalyst and increase in the surface area of the reactants
41
Which of the following is NOT a redox reaction?
คำตอบ
(C)
Ca(HCO3)2 → CaCO3 + H2O + CO2
42
0.16g of methane when burnt raises the temperature of 100g of water by 40°C. What is the of combustion of methane when if the heat capacity of water is 4.2 Jg-1°C-1?
(CH4 = 16)
คำตอบ
(E)
1,680 kJ mol-1
43
Which of the following processes NOT lead to a chemical change?
คำตอบ
(B)
Stirring sodium carbonate in water
44
Brass is an alloy containing copper and?
คำตอบ
(A)
zinc
45
The number of grammes of potassium hydroxide in 250cm3 of one molar solution is?
(K = 39, O = 16, H = 1)
