Đề thi bằng Tiếng Anh môn Hóa học Lớp 11 - Năm học 2020-2021 - Sở GD&ĐT Nam Định (Có đáp án)

 NAM DINH DEPARTMENT OF CONTEST OF MATH AND SCIENCE IN ENGLISH
 EDUCATION AND TRAINING School year: 2020 - 2021
 Subject: CHEMISTRY – Grade 11 
 OFFICIAL Time allowed: 90 minutes
 CODE: 321
PART I (7.0 points)
Write the correct answer (A, B, C or D) for each of the following questions in the correspondingly numbered space on 
your answer sheet. 
Question 1. Which of the following is a chemical change?
 A. Dissolution of table salt in water.B. Boiling of water.
 C. Rusting of iron.D. Freezing of water.
Question 2. What is the relationship between the two compounds below?
CH3CH2CH(CH3)CH2CH3 and CH3CH2CH2CH(CH3)CH3 
 A. Identical compounds.B. Structural constitutional isomers.
 C. Geometric isomers.D. Stereoisomers.
Question 3. Which element does NOT have multiple allotropes?
 A. Oxygen.B. Fluorine.C. Carbon. D. Phosphorus.
Question 4. An alkane contains 14 hydrogen atoms. How many carbon atoms does it contain?
 A. 6.B. 5.C. 30. D. 8.
Question 5. What is the mass number of an atom which contains 14 protons, 14 electrons, and 15 neutrons?
 A. 14.B. 28.C. 43. D. 29.
Question 6. A pH greater than 7 indicates
 A. alkalinity.B. purity of the sample.C. presence of ions. D. acidity.
Question 7. The diagrams below represent the progress of a reaction of A → B, with molecules of A represented by solid 
circles and molecules of B represented by open circles. Which statement best describes the reaction at t = 1000 s?
 A. The reaction is not at equilibrium because not all of A has been consumed.
 B. The reaction is not at equilibrium because the positions of the molecules are still changing.
 C. The reaction is at equilibrium because the concentrations of A and B are no longer changing.
 D. The reaction is not at equilibrium because the concentrations of A and B are not equal.
Question 8. Which hydrocarbon is 84.2% carbon by mass?
 A. C4H10.B. CH 4.C. C 8H18.D. C 2H6.
Question 9. The phase transition from solid to gas without passing through the liquid state is called
 A. sublimation.B. boiling.C. melting. D. condensation.
Question 10. A gas phase atom with an atomic number of 26 loses three electrons. What is the electron configuration of 
the resulting gas phase ion? 
 A. 1s22s22p63s23p63d5.B. 1s 22s22p63s23p63d44s1. C. 1s22s22p63s23p53d54s1.D. 1s 22s22p63s23p63d34s2.
Question 11. How many σ and π bonds are in 1,3-butadiene, H2C=CH-CH=CH2?
 A. 7 σ and 2 π bonds.B. 2 σ and 7 π bonds.C. 2 σ and 9 π bonds. D. 9 σ and 2 π bonds.
Question 12. Choose the most correct definition.
 A. Organic compounds are based on carbon, and they usually contain carbon-nitrogen and carbon-silicon bonds.
 B. Organic compounds are based on nitrogen, and they usually contain carbon-nitrogen and carbon-hydrogen bonds.
 C. Organic compounds are based on hydrogen, and they usually contain carbon- hydrogen and carbon-oxygen bonds.
 Page 1/4 – CODE 321 D. Organic compounds are based on carbon, and they usually contain carbon- hydrogen and carbon-carbon bonds.
Question 13. A white ionic solid is dissolved in water. Addition of a solution of sodium chloride to this solution results in 
a white precipitate. What was the cation in the original ionic solid?
 A. Ca2+.B. Na +.C. Fe 3+. D. Ag+.
Question 14. Which set of properties best describes a small alkane, such as ethane?
 A. polar, low boiling point, soluble in water, not very reactive.
 B. polar, high boiling point, insoluble in water, extremely reactive.
 C. non-polar, high boiling point, insoluble in water, extremely reactive.
 D. non-polar, low boiling point, insoluble in water, not very reactive.
Question 15. Which of the following is true?
 A. Reduction is the gain of electrons and the increase in oxidation number.
 B. Reduction is the loss of electrons and the increase in oxidation number.
 C. Reduction is the loss of electrons and the decrease in oxidation number.
 D. Reduction is the gain of electrons and the decrease in oxidation number.
Question 16. How many hydroxide ions are in 2.5 mol Mg(OH)2?
 A. 6.0 x 1023.B. 1.5 x 10 24.C. 3.0 x 10 24.D. 3.0 x 10 23.
Question 17. Which combination of atoms can form a non-polar covalent bond?
 A. Na and Br.B. N and Mg.C. O and O. D. H and Cl.
Question 18. Which of the following solutions (C = 0.1 mol/L) has the highest pH value?
 A. ammonia.B. potassium hydroxide.C. acetic acid. D. hydrochloric acid.
Question 19. When a solution of barium hydroxide is mixed with a solution of copper (II) nitrate, what is observed?
 A. Evolution of a colorless gas.B. Precipitation of a colored solid.
 C. Neither precipitation nor gas evolution.D. Precipitation of a colorless solid.
Question 20. The oxidation number of carbon in a compound cannot be
 A. +4.B. +2.C. -4. D. +6.
Question 21. The graph below shows the forward and reverse rates for a reaction as a function of time. At time t, a catalyst 
is added to the system, and the forward reaction rate is observed to change as indicated by the solid curve. Which dashed 
curve best indicates how the reverse reaction rate changes?
 A. D.B. A.C. B. D. C.
Question 22. Which is the best way to prepare 500 mL of a 2.00 M solution of aqueous H2SO4 from deionized water 
 -1 -1
(density = 1.00 g.mL ) and concentrated H2SO4 (density = 1.84 g.mL )?
 A. Weigh 98.1 g concentrated sulfuric acid into a 100-mL beaker, then slowly pour the H2SO4 into a 500-mL beaker 
with about 250 mL deionized water in it. Pour this solution into a 500-mL volumetric flask and fill to the mark with 
deionized water and mix.
 B. Weigh 98.1 g concentrated sulfuric acid into a 500-mL volumetric flask, slowly add deionized water to the mark, 
and mix.
 C. Weigh 98.1 g concentrated sulfuric acid into a 500-mL beaker, then slowly add deionized water to the beaker, with 
occasional swirling, until the liquid reaches the 500 mL mark.
 D. Weigh 446.6 g deionized water into a 500-mL volumetric flask, fill to the mark with concentrated sulfuric acid, 
and mix.
Question 23. Which one of the following sets of ions can coexist at large in an aqueous solution?
 + - - 2+ 2+ 2- + 2+ - + + -
 A. NH4 , HCO3 , OH .B. Ba , Cu , SO4 .C. Na , Ca , NO3 .D. Ag , H , Cl .
Question 24. Bromate ion and bromide ion react to form bromine in acidic solution. When the reaction is balanced, which 
statement about H+ (aq) is correct?
 + - -
 H (aq) + BrO3 (aq) + Br (aq) → Br2 (aq) + H2O(l)
 A. Its coefficient is twice the coefficient of Br-(aq).
 B. Its coefficient is twice the coefficient of Br2(aq).
 Page 2/4 – CODE 321 -
 C. Its coefficient is twice the coefficient of BrO3 (aq).
 -
 D. Its coefficient is the sum of the coefficients of BrO3 (aq) and H2O(l).
Question 25. A test tube contains a clear, colourless salt solution. A few drops of silver nitrate solution are added to the 
solution and a pale yellow precipitate forms. Which one of the following salts was dissolved in the original solution?
 A. K2SO4.B. KI.C. Na 2CO3.D. NaCl.
Question 26. A 5.0 g sample of calcium nitrate (Ca(NO3)2) contaminated with silica (SiO2) is found to contain 1.0 g 
calcium. What is the mass percent purity of calcium nitrate in the sample?
 A. 73%.B. 82%.C. 24%. D. 20%.
Question 27. A 10.00 g sample of a compound containing only carbon, hydrogen and oxygen forms 23.98 g CO2 and 4.91 
g H2O upon complete combustion. What is the empirical formula of the compound?
 A. C3H3O.B. C 6H6O.C. C 2HO. D. C6H3O2.
Question 28. A sample of lemon juice has a pH of 2. A sample of an ammonia cleaner has a pH of 11. If the two samples 
are combined, what ratio by volume of lemon juice to ammonia cleaner is needed to yield a neutral solution?
 A. 1 : 10.B. 1 : 100.C. 1 : 1000. D. 10 : 1.
 o
Question 29. A 2.5 L sample of butane gas (C4H10), measured at 22.0 C and 1.20 atm pressure, is combusted completely 
and the carbon dioxide gas is collected at the same pressure and temperature. What volume of CO2 is produced?
 A. 2.5 L.B. 9.0 L.C. 22.5 L. D. 10.0 L.
Question 30. C(s) + H2O(g) ƒ CO(g) + H2(g) ∆H > 0
For the system above at equilibrium, which changes will increase the amount of H2(g)?
 I. Adding C(s)
 II. Increasing the volume of the container
 III. Increasing the temperature
 A. I, II and III.B. I only.C. II and III only. D. III only.
Question 31. Descicated anhydrous calcium chloride was stored in an improperly closed vessel. Thus it was partially 
hydrated again. A 150 g sample of this material was completely dissolved in 80 g of hot water, then the solution was 
 o o
cooled down to 20 C. On cooling, 40.9 g of CaCl2.6H2O precipitated. Solubility of calcium chloride at 20 C is 74.5 g of 
CaCl2/100 g of water. Determine the water content of calcium chloride in the 150 g sample (moles of water per 1 mole of 
CaCl2).
 A. 2.70.B. 3.09.C. 2.54. D. 2.95.
Question 32. A 12.2 g sample containing rock salt (NaCl) and sylvinite (KCl.NaCl) was dissolved in 100 mL of water. 
After the insoluble impurities were removed by filtering, the solution had a volume of 104 mL. A 10.0 ml aliquot of this 
solution was added to an excess of acidified aqueous silver nitrate. The resulting precipitate was filtered, dried, and 
weighed. Its mass was found to be 2.53 g. Another 5.00 mL aliquot of the solution was evaporated to dryness to yield 
0.543 g of a solid residue. The mass percentage of KCl.NaCl in the sample is
 A. 45.4%.B. 62.0%.C. 38.0%. D. 38.2%.
Question 33. A student wishes to prepare a solution with a final concentration of Na+ = 0.50 M and a final concentration 
 -
of HCO3 = 0.10 M by taking some NaOH and some trona (Na2CO3.NaHCO3.2H2O) and diluting with water to a final 
volume of 1.00 L. How much NaOH and trona are required?
 A. 0.05 mol NaOH, 0.15 mol trona.
 B. 0.35 mol NaOH, 0.05 mol trona.
 C. 0.20 mol NaOH, 0.10 mol trona.
 + -
 D. A solution cannot be prepared with the desired concentration of Na and HCO3 using only NaOH and trona.
Question 34. You know that salty water is particularly healthy and you want to raise the mass content of chloride in the 
pool water to 1%. 1 kg of pure salt costs 3500 VND. The pool has a base area of 5m x 6m and is filled up to 1.8m. The 
density of the water delivered by the company amounts to 1 g/cm3. Assume an original mass content of 25 mg of 
chloride/100 mL of water. The expense to reach the wanted mass concentration by adding pure salt is
 A. 2.36 million VND.B. 3.09 million VND.C. 2.41 million VND. D. 1.86 million VND.
Question 35. Phosphoric acid can be manufactured according to the following reaction:
 Ca3(PO4)2 + 3 SiO2 + 5 C + 5 O2 + 3 H2O → 2 H3PO4 + 3 CaSiO3 + 5 CO2
If equal masses of calcium phosphate and silica are reacted with excess carbon, oxygen and water to produce 1.00 x 103 
kg phosphoric acid, what mass of calcium phosphate was used, assuming 100% yield?
 A. 1581.6 kg.B. 3163.3 kg.C. 1583.2 kg. D. 1054.4 kg.
 Page 3/4 – CODE 321 PART II (3.0 points)
Write the solutions to the following questions in the provided space on your anwer sheet.
 Question 1. The following picture shows the experiment to prepare Cl2 in the lab.
 1. Write a balanced equation to prepare Cl2 in the lab.
 2. What are the names of the chemicals used in position (1), (2), (3), (4), (5), (6)?
 Question 2. 
 1. A 1.92 L sample (at STP) of a gaseous mixture of hydrocarbons that is 12.6% elemental hydrogen (by mass) was 
burnt in an excess of oxygen. The volatile combustion products were dried and bubbled through 400 mL of a 4.82% (by 
mass) NaOH solution with a density of 1.05 g/cm3.
 a. Calculate the initial mass of the hydrocarbon mixture given that its specific gravity relative to nitrogen is 2.27.
 b. What volume is occupied by the resulting carbon dioxide at N.T.P 
 c. Determine the qualitative composition and mass percentage of substances in the solution obtained by bubbling the 
 carbon dioxide gas through the NaOH solution.
 2. Explain and describe what happens when the excess of carbon dioxide gas is slowly bubbled through limewater.
 Question 3.
 1. A beaker with 12.00 g of CuSO4 was set aside on vacation. One week later, precisely 1/3 of the salt transformed into 
 3
pentahydrate (CuSO4.5H2O). 90.00 cm of water was casually slooshed into the beaker during cleanup after vacation. After 
that all the charge was transferred into a flask filled with 300.0 cm3 0.0400 M NaOH solution. A formed precipitate was 
separated and heated until a black substance was formed and its mass remained stable. Assuming the density of water is 1 
g/cm3. 
 a. Calculate the percentage of CuSO4 in the formed solution after adding water.
 b. Write all the reactions taking place and name the compounds that contain copper. Calculate the mass of the 
 substance after heating.
 2. A sample of gaseous hydrocarbon occupying 5.377 litres at N.T.P completely burnt in air produced 19.712 grams of 
CO2 and 8.064 grams of H2O. Find the molecular formula and draw the electron formula of the hydrocarbon. 
 Note: N.T.P - Normal Temperature and Pressure - is defined as gas at 20oC and 1 atm.
 S.T.P – Standard Temperature and Pressure - is defined as gas at 0oC and 1 atm.
 -THE END-
Student’s full name: Student’s ID: 
First observer’s name and signature: Second observer’s name and signature: 
 Page 4/4 – CODE 321 NAM DINH DEPARTMENT OF CONTEST OF MATH AND SCIENCE IN ENGLISH
 EDUCATION AND TRAINING School year: 2020 - 2021
 Subject: CHEMISTRY – Grade 11 
 OFFICIAL Time allowed: 90 minutes
 CODE: 323
PART I (7.0 points)
Write the correct answer (A, B, C or D) for each of the following questions in the correspondingly numbered space on 
your answer sheet. 
Question 1. Which hydrocarbon is 84.2% carbon by mass?
 A. CH4.B. C 4H10.C. C 2H6.D. C 8H18.
Question 2. A gas phase atom with an atomic number of 26 loses three electrons. What is the electron configuration of the 
resulting gas phase ion? 
 A. 1s22s22p63s23p63d5.B. 1s 22s22p63s23p63d34s2.C. 1s22s22p63s23p53d54s1.D. 1s 22s22p63s23p63d44s1.
Question 3. When a solution of barium hydroxide is mixed with a solution of copper (II) nitrate, what is observed?
 A. Precipitation of a colored solid.B. Neither precipitation nor gas evolution.
 C. Precipitation of a colorless solid.D. Evolution of a colorless gas.
Question 4. The phase transition from solid to gas without passing through the liquid state is called
 A. boiling.B. condensation.C. sublimation. D. melting.
Question 5. An alkane contains 14 hydrogen atoms. How many carbon atoms does it contain?
 A. 5.B. 30.C. 8. D. 6.
Question 6. Which of the following is a chemical change?
 A. Dissolution of table salt in water.B. Boiling of water.
 C. Rusting of iron.D. Freezing of water.
Question 7. Which set of properties best describes a small alkane, such as ethane?
 A. polar, low boiling point, soluble in water, not very reactive.
 B. polar, high boiling point, insoluble in water, extremely reactive.
 C. non-polar, low boiling point, insoluble in water, not very reactive.
 D. non-polar, high boiling point, insoluble in water, extremely reactive.
Question 8. Which of the following is true?
 A. Reduction is the gain of electrons and the increase in oxidation number.
 B. Reduction is the loss of electrons and the increase in oxidation number.
 C. Reduction is the loss of electrons and the decrease in oxidation number.
 D. Reduction is the gain of electrons and the decrease in oxidation number.
Question 9. What is the mass number of an atom which contains 14 protons, 14 electrons, and 15 neutrons?
 A. 43.B. 14.C. 29. D. 28.
Question 10. A white ionic solid is dissolved in water. Addition of a solution of sodium chloride to this solution results in 
a white precipitate. What was the cation in the original ionic solid?
 A. Ag+.B. Na +.C. Ca 2+.D. Fe 3+.
Question 11. How many σ and π bonds are in 1,3-butadiene, H2C=CH-CH=CH2?
 A. 2 σ and 9 π bonds.B. 2 σ and 7 π bonds.C. 9 σ and 2 π bonds. D. 7 σ and 2 π bonds.
Question 12. Which combination of atoms can form a non-polar covalent bond?
 A. H and Cl.B. Na and Br.C. N and Mg. D. O and O.
Question 13. Choose the most correct definition.
 A. Organic compounds are based on hydrogen, and they usually contain carbon- hydrogen and carbon-oxygen bonds.
 B. Organic compounds are based on carbon, and they usually contain carbon-nitrogen and carbon-silicon bonds.
 C. Organic compounds are based on carbon, and they usually contain carbon- hydrogen and carbon-carbon bonds.
 D. Organic compounds are based on nitrogen, and they usually contain carbon-nitrogen and carbon-hydrogen bonds.
Question 14. Which element does NOT have multiple allotropes?
 A. Carbon.B. Fluorine.C. Oxygen. D. Phosphorus.
Question 15. The diagrams below represent the progress of a reaction of A → B, with molecules of A represented by solid 
circles and molecules of B represented by open circles. Which statement best describes the reaction at t =1000s?
 Page 1/4 – CODE 323 
 A. The reaction is not at equilibrium because not all of A has been consumed.
 B. The reaction is not at equilibrium because the positions of the molecules are still changing.
 C. The reaction is not at equilibrium because the concentrations of A and B are not equal.
 D. The reaction is at equilibrium because the concentrations of A and B are no longer changing.
Question 17. The oxidation number of carbon in a compound cannot be
 A. +4.B. -4.C. +2. D. +6.
Question 18. Which of the following solutions (C = 0.1 mol/L) has the highest pH value?
 A. ammonia.B. acetic acid. C. potassium hydroxide. D. hydrochloric acid.
Question 19. What is the relationship between the two compounds below?
CH3CH2CH(CH3)CH2CH3 and CH3CH2CH2CH(CH3)CH3 
 A. Structural constitutional isomers.B. Geometric isomers.
 C. Stereoisomers.D. Identical compounds.
Question 20. A pH greater than 7 indicates
 A. presence of ions.B. acidity.C. purity of the sample. D. alkalinity.
Question 21. A test tube contains a clear, colourless salt solution. A few drops of silver nitrate solution are added to the 
solution and a pale yellow precipitate forms. Which one of the following salts was dissolved in the original solution? 
 A. KI.B. Na 2CO3.C. NaCl.D. K 2SO4.
Question 22. Bromate ion and bromide ion react to form bromine in acidic solution. When the reaction is balanced, which 
statement about H+ (aq) is correct?
 + - -
 H (aq) + BrO3 (aq) + Br (aq) → Br2 (aq) + H2O(l)
 -
 A. Its coefficient is twice the coefficient of BrO3 (aq).
 -
 B. Its coefficient is the sum of the coefficients of BrO3 (aq) and H2O(l).
 C. Its coefficient is twice the coefficient of Br2(aq).
 D. Its coefficient is twice the coefficient of Br-(aq).
Question 23. Which is the best way to prepare 500 mL of a 2.00 M solution of aqueous H2SO4 from deionized water 
 -1 -1
(density = 1.00 g.mL ) and concentrated H2SO4 (density = 1.84 g.mL )?
 A. Weigh 98.1 g concentrated sulfuric acid into a 500-mL beaker, then slowly add deionized water to the beaker, with 
occasional swirling, until the liquid reaches the 500 mL mark.
 B. Weigh 98.1 g concentrated sulfuric acid into a 100-mL beaker, then slowly pour the H2SO4 into a 500-mL beaker 
with about 250 mL deionized water in it. Pour this solution into a 500-mL volumetric flask and fill to the mark with 
deionized water and mix.
 C. Weigh 446.6 g deionized water into a 500-mL volumetric flask, fill to the mark with concentrated sulfuric acid, 
and mix.
 D. Weigh 98.1 g concentrated sulfuric acid into a 500-mL volumetric flask, slowly add deionized water to the mark, 
and mix.
Question 24. The graph below shows the forward and reverse rates for a reaction as a function of time. At time t, a catalyst 
is added to the system, and the forward reaction rate is observed to change as indicated by the solid curve. Which dashed 
curve best indicates how the reverse reaction rate changes?
 A. A.B. B.C. D. D. C.
 Page 2/4 – CODE 323 Question 25. Which one of the following sets of ions can coexist at large in an aqueous solution?
 + - - + 2+ - 2+ 2+ 2- + + -
 A. NH4 , HCO3 , OH .B. Na , Ca , NO3 .C. Ba , Cu , SO4 .D. Ag , H , Cl .
Question 26. C(s) + H2O(g) ƒ CO(g) + H2(g) ∆H > 0
For the system above at equilibrium, which changes will increase the amount of H2(g)?
 I. Adding C(s)
 II. Increasing the volume of the container
 III. Increasing the temperature
 A. III only.B. II and III only.C. I only. D. I, II and III.
Question 27. A 5.0 g sample of calcium nitrate (Ca(NO3)2) contaminated with silica (SiO2) is found to contain 1.0 g 
calcium. What is the mass percent purity of calcium nitrate in the sample?
 A. 73%.B. 24%.C. 20%. D. 82%.
Question 28. A sample of lemon juice has a pH of 2. A sample of an ammonia cleaner has a pH of 11. If the two samples 
are combined, what ratio by volume of lemon juice to ammonia cleaner is needed to yield a neutral solution?
 A. 1 : 100.B. 1 : 1000.C. 10 : 1. D. 1 : 10.
Question 29. A 10.00 g sample of a compound containing only carbon, hydrogen and oxygen forms 23.98 g CO2 and 4.91 
g H2O upon complete combustion. What is the empirical formula of the compound?
 A. C6H3O2.B. C 3H3O.C. C 6H6O.D. C 2HO.
 o
Question 30. A 2.5 L sample of butane gas (C4H10), measured at 22.0 C and 1.20 atm pressure, is combusted completely 
and the carbon dioxide gas is collected at the same pressure and temperature. What volume of CO2 is produced?
 A. 2.5 L.B. 9.0 L.C. 10.0 L. D. 22.5 L.
Question 31. A 12.2 g sample containing rock salt (NaCl) and sylvinite (KCl.NaCl) was dissolved in 100 mL of water. 
After the insoluble impurities were removed by filtering, the solution had a volume of 104 mL. A 10.0 ml aliquot of this 
solution was added to an excess of acidified aqueous silver nitrate. The resulting precipitate was filtered, dried, and 
weighed. Its mass was found to be 2.53 g. Another 5.00 mL aliquot of the solution was evaporated to dryness to yield 
0.543 g of a solid residue. The mass percentage of KCl.NaCl in the sample is
 A. 45.4%.B. 38.0%.C. 38.2%. D. 62.0%.
Question 32. Descicated anhydrous calcium chloride was stored in an improperly closed vessel. Thus it was partially 
hydrated again. A 150 g sample of this material was completely dissolved in 80 g of hot water, then the solution was 
 o o
cooled down to 20 C. On cooling, 40.9 g of CaCl2.6H2O precipitated. Solubility of calcium chloride at 20 C is 74.5 g of 
CaCl2/100 g of water. Determine the water content of calcium chloride in the 150 g sample (moles of water per 1 mole of 
CaCl2).
 A. 2.95.B. 2.54.C. 2.70. D. 3.09.
Question 33. Phosphoric acid can be manufactured according to the following reaction:
 Ca3(PO4)2 + 3 SiO2 + 5 C + 5 O2 + 3 H2O → 2 H3PO4 + 3 CaSiO3 + 5 CO2
If equal masses of calcium phosphate and silica are reacted with excess carbon, oxygen and water to produce 1.00 x 103 
kg phosphoric acid, what mass of calcium phosphate was used, assuming 100% yield?
 A. 3163.3 kg.B. 1583.2 kg.C. 1581.6 kg. D. 1054.4 kg.
Question 34. A student wishes to prepare a solution with a final concentration of Na+ = 0.50 M and a final concentration 
 -
of HCO3 = 0.10 M by taking some NaOH and some trona (Na2CO3.NaHCO3.2H2O) and diluting with water to a final 
volume of 1.00 L. How much NaOH and trona are required?
 A. 0.20 mol NaOH, 0.10 mol trona.
 B. 0.05 mol NaOH, 0.15 mol trona.
 + -
 C. A solution cannot be prepared with the desired concentration of Na and HCO3 using only NaOH and trona.
 D. 0.35 mol NaOH, 0.05 mol trona.
Question 35. You know that salty water is particularly healthy and you want to raise the mass content of chloride in the 
pool water to 1%. 1 kg of pure salt costs 3500 VND. The pool has a base area of 5m x 6m and is filled up to 1.8m. The 
density of the water delivered by the company amounts to 1 g/cm3. Assume an original mass content of 25 mg of 
chloride/100 mL of water. The expense to reach the wanted mass concentration by adding pure salt is
 A. 3.09 million VND.B. 2.41 million VND.C. 2.36 million VND. D. 1.86 million VND.
 Page 3/4 – CODE 323 PART II (3.0 points)
Write the solutions to the following questions in the provided space on your anwer sheet.
 Question 1. The following picture shows the experiment to prepare Cl2 in the lab.
 1. Write a balanced equation to prepare Cl2 in the lab.
 2. What are the names of the chemicals used in position (1), (2), (3), (4), (5), (6)?
 Question 2. 
 1. A 1.92 L sample (at STP) of a gaseous mixture of hydrocarbons that is 12.6% elemental hydrogen (by mass) was 
burnt in an excess of oxygen. The volatile combustion products were dried and bubbled through 400 mL of a 4.82% (by 
mass) NaOH solution with a density of 1.05 g/cm3.
 a. Calculate the initial mass of the hydrocarbon mixture given that its specific gravity relative to nitrogen is 2.27.
 b. What volume is occupied by the resulting carbon dioxide at N.T.P 
 c. Determine the qualitative composition and mass percentage of substances in the solution obtained by bubbling the 
 carbon dioxide gas through the NaOH solution.
 2. Explain and describe what happens when the excess of carbon dioxide gas is slowly bubbled through limewater.
 Question 3. 
 1. A beaker with 12.00 g of CuSO4 was set aside on vacation. One week later, precisely 1/3 of the salt transformed into 
 3
pentahydrate (CuSO4.5H2O). 90.00 cm of water was casually slooshed into the beaker during cleanup after vacation. After 
that all the charge was transferred into a flask filled with 300.0 cm3 0.0400 M NaOH solution. A formed precipitate was 
separated and heated until a black substance was formed and its mass remained stable. Assuming the density of water is 1 
g/cm3. 
 a. Calculate the percentage of CuSO4 in the formed solution after adding water.
 b. Write all the reactions taking place and name the compounds that contain copper. Calculate the mass of the 
 substance after heating.
 2. A sample of gaseous hydrocarbon occupying 5.377 litres at N.T.P completely burnt in air produced 19.712 grams of 
CO2 and 8.064 grams of H2O. Find the molecular formula and draw the electron formula of the hydrocarbon. 
 Note: N.T.P - Normal Temperature and Pressure - is defined as gas at 20oC and 1 atm.
 S.T.P – Standard Temperature and Pressure - is defined as gas at 0oC and 1 atm.
 -THE END-
Student’s full name: Student’s ID: 
First observer’s name and signature: Second observer’s name and signature: 
 Page 4/4 – CODE 323 NAM DINH DEPARTMENT OF CONTEST OF MATH AND SCIENCE IN ENGLISH
 EDUCATION AND TRAINING School year: 2020 - 2021
 Subject: CHEMISTRY – Grade 11 
 OFFICIAL Time allowed: 90 minutes
 CODE: 325
PART I (7.0 points)
Write the correct answer (A, B, C or D) for each of the following questions in the correspondingly numbered space on 
your answer sheet. 
Question 1. Which of the following is true?
 A. Reduction is the loss of electrons and decrease in oxidation number.
 B. Reduction is the loss of electrons and increase in oxidation number.
 C. Reduction is the gain of electrons and decrease in oxidation number.
 D. Reduction is the gain of electrons and increase in oxidation number.
Question 2. How many hydroxide ions are in 2.5 mol Mg(OH)2?
 A. 6.0 x 1023.B. 3.0 x 10 23.C. 1.5 x 10 24.D. 3.0 x 10 24.
Question 3. An alkane contains 14 hydrogen atoms. How many carbon atoms does it contain?
 A. 30.B. 6.C. 5. D. 8.
Question 4. Which element does NOT have multiple allotropes?
 A. Fluorine.B. Carbon.C. Oxygen. D. Phosphorus.
Question 5. Which hydrocarbon is 84.2% carbon by mass?
 A. C8H18.B. CH 4.C. C 2H6.D. C 4H10.
Question 6. The oxidation number of carbon in a compound cannot be
 A. +2.B. -4.C. +6. D. +4.
Question 7. A gas phase atom with an atomic number of 26 loses three electrons. What is the electron configuration of the 
resulting gas phase ion? 
 A. 1s22s22p63s23p63d5.B. 1s 22s22p63s23p63d34s2. C. 1s22s22p63s23p63d44s1.D. 1s 22s22p63s23p53d54s1.
Question 8. How many σ and π bonds are in 1,3-butadiene, H2C=CH-CH=CH2?
 A. 2 σ and 7 π bonds.B. 7 σ and 2 π bonds.C. 9 σ and 2 π bonds. D. 2 σ and 9 π bonds.
Question 9. Which combination of atoms can form a non-polar covalent bond?
 A. H and Cl.B. N and Mg.C. Na and Br. D. O and O.
Question 10. What is the relationship between the two compounds below?
CH3CH2CH(CH3)CH2CH3 and CH3CH2CH2CH(CH3)CH3 
 A. Identical compounds.B. Geometric isomers.
 C. Structural constitutional isomers.D. Stereoisomers.
Question 11. Choose the most correct definition.
 A. Organic compounds are based on carbon, and they usually contain carbon-nitrogen and carbon-silicon bonds.
 B. Organic compounds are based on hydrogen, and they usually contain carbon- hydrogen and carbon-oxygen bonds.
 C. Organic compounds are based on nitrogen, and they usually contain carbon-nitrogen and carbon-hydrogen bonds.
 D. Organic compounds are based on carbon, and they usually contain carbon- hydrogen and carbon-carbon bonds.
Question 12. The phase transition from solid to gas without passing through the liquid state is called
 A. sublimation.B. melting.C. boiling. D. condensation.
Question 13. When a solution of barium hydroxide is mixed with a solution of copper (II) nitrate, what is observed?
 A. Precipitation of a colored solid.B. Precipitation of a colorless solid.
 C. Neither precipitation nor gas evolution.D. Evolution of a colorless gas.
Question 14. What is the mass number of an atom which contains 14 protons, 14 electrons, and 15 neutrons?
 A. 14.B. 43.C. 28. D. 29.
Question 15. The diagrams below represent the progress of a reaction of A → B, with molecules of A represented by solid 
circles and molecules of B represented by open circles. Which statement best describes the reaction at t =1000s?
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 A. The reaction is not at equilibrium because the positions of the molecules are still changing.
 B. The reaction is at equilibrium because the concentrations of A and B are no longer changing.
 C. The reaction is not at equilibrium because the concentrations of A and B are not equal.
 D. The reaction is not at equilibrium because not all of A has been consumed.
Question 16. A pH greater than 7 indicates
 A. acidity.B. alkalinity.C. purity of the sample. D. presence of ions.
Question 17. Which set of properties best describes a small alkane, such as ethane?
 A. polar, high boiling point, insoluble in water, extremely reactive.
 B. non-polar, low boiling point, insoluble in water, not very reactive.
 C. polar, low boiling point, soluble in water, not very reactive.
 D. non-polar, high boiling point, insoluble in water, extremely reactive.
Question 18. Which of the following is a chemical change?
 A. Rusting of iron.B. Boiling of water.
 C. Freezing of water.D. Dissolution of table salt in water.
Question 19. Which of the following solutions (C = 0.1 mol/L) has the highest pH value?
 A. potassium hydroxide.B. acetic acid. C. hydrochloric acid. D. ammonia.
Question 20. A white ionic solid is dissolved in water. Addition of a solution of sodium chloride to this solution results in 
a white precipitate. What was the cation in the original ionic solid?
 A. Na+.B. Ca 2+.C. Fe 3+. D. Ag+.
Question 21. Which one of the following sets of ions can coexist at large in an aqueous solution?
 + - - 2+ 2+ 2- + 2+ - + + -
 A. NH4 , HCO3 , OH .B. Ba , Cu , SO4 .C. Na , Ca , NO3 .D. Ag , H , Cl .
Question 22. A test tube contains a clear, colourless salt solution. A few drops of silver nitrate solution are added to the 
solution and a pale yellow precipitate forms. Which one of the following salts was dissolved in the original solution? A. 
NaCl.B. K 2SO4.C. Na 2CO3.D. KI.
Question 23. The graph below shows the forward and reverse rates for a reaction as a function of time. At time t, a catalyst 
is added to the system, and the forward reaction rate is observed to change as indicated by the solid curve. Which dashed 
curve best indicates how the reverse reaction rate changes?
 A. D.B. A.C. C. D. B.
Question 24. Bromate ion and bromide ion react to form bromine in acidic solution. When the reaction is balanced, which 
statement about H+ (aq) is correct?
 + - -
 H (aq) + BrO3 (aq) + Br (aq) → Br2 (aq) + H2O(l)
 A. Its coefficient is twice the coefficient of Br-(aq).
 -
 B. Its coefficient is the sum of the coefficients of BrO3 (aq) and H2O(l).
 -
 C. Its coefficient is twice the coefficient of BrO3 (aq).
 D. Its coefficient is twice the coefficient of Br2(aq).
Question 25. Which is the best way to prepare 500 mL of a 2.00 M solution of aqueous H2SO4 from deionized water 
 -1 -1
(density = 1.00 g.mL ) and concentrated H2SO4 (density = 1.84 g.mL )?
 A. Weigh 98.1 g concentrated sulfuric acid into a 500-mL volumetric flask, slowly add deionized water to the mark, 
and mix.
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