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Grade 12 Chemistry national exam, 2011 E.C. (2019 G.C.)

77 questions · 120 minutes. The first 5 answers are shown with explanations; sit the whole paper timed in the app to get your score and the textbook page behind every question.

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1.What aspect of the modern view of atomic structure was proved by Rutherford's gold foil experiment?
- A. The existence of the nucleus.
- B. The charge on an electron.
- C. The charge on an particle.
- D. The existence of electrons. α
Answer: A. The question tests what Rutherford’s gold foil experiment showed about the atom. Most alpha particles passed through, but a few were strongly deflected, showing that atoms have a small, dense nucleus. B concerns the charge on an electron. C concerns the charge of a particle, not the discovery of the nucleus. D concerns the existence of electrons, which the experiment did not prove. Textbook: Grade 9, unit 3 · section 3.4.
2.Which of these compounds is propanoic acid?
- A. CH₃CH₂COOCH₃
- B. CH₃CH₂COH
- C. CH₃CH₂CH₂OH
- D. CH₃CH₂COOH
Answer: D. The key idea is that a carboxylic acid contains the group $\mathrm{-COOH}$. Propanoic acid has three carbon atoms and the formula $\mathrm{CH_3CH_2COOH}$. A is an ester, B is an aldehyde, and C is an alcohol, so none of them is propanoic acid. Textbook: Grade 11, unit 6 · section 6.4.
3.Fats and oils can be classified as___________.
- A. carbohydrates
- B. acids
- C. esters
- D. alcohols
Answer: C. This question tests the chemical class of fats and oils. Fats and oils are esters made from glycerol and fatty acids, so C is correct. They are not carbohydrates; they are not acids themselves; they are not alcohols. Textbook: Grade 11, unit 6 · section 6.6.4.
4.What does it mean by H = negative for a given process?
- A. The process is endothermic
- B. The process is exothermic
- C. The process is adiabatic
- D. The process is equithermic
Answer: B. The key idea is that a negative enthalpy change means heat is released. When $\Delta H<0$, the process is exothermic, so B is correct. A is wrong because an endothermic process absorbs heat and has $\Delta H>0$. C is wrong because adiabatic means no heat is transferred. D is wrong because equithermic is not the term for a negative enthalpy change. Textbook: Grade 10, unit 4 · section 4.1.
5.The oxidation state of chlorine in HClO₄ is:
- A. +1
- B. +3
- C. +5
- D. +7
Answer: D. The question tests how to find an oxidation state in a neutral compound. In $\mathrm{HClO_4}$, hydrogen is $+1$ and each oxygen is $-2$, so $x+1+4(-2)=0$ and $x=+7$. A, $+1$, is the oxidation state of hydrogen here. B, $+3$, and C, $+5$, do not make the total oxidation state zero. Textbook: Grade 10, unit 1 · section 1.4.
6.Which substance is used to lower the melting point of aluminum oxide ore in the electrolytic extraction of aluminum?
- A. Cryolite
- B. Bauxite
- C. Hematite
- D. Magnetite
Answer, explanation and textbook page: open in the app.
7.The metal extracted from limestone, chalk and marble is___________.
- A. Sodium
- B. Calcium
- C. Zinc
- D. Chromium
Answer, explanation and textbook page: open in the app.
8.Which one of the following is NOT a condensation polymer?
- A. Neoprene
- B. Polyamides
- C. Polyester
- D. Nylon
Answer, explanation and textbook page: open in the app.
9.Which of the following compounds does NOT contain both ionic and covalent bond?
- A. NH₄NO₃
- B. CH₃CO₂H
- C. NH₄Cl
- D. Na₂CO₃
Answer, explanation and textbook page: open in the app.
10.Acetylsalicylic acid (aspirin) has the structural formula: Which functional group (groups) is (are) present in aspirin? [Figure: A chemical structural formula of acetylsalicylic acid (aspirin). It consists of a benzene ring with two adjacent substituents on the right side: the upper-right substituent shows a bond from the ring vertex to a group labeled '-COH' with a vertical double bond to an oxygen atom ('=O') above it; the lower-right substituent shows a bond from the ring vertex to '-O-CH3' with a vertical double bond to an oxygen atom ('=O') below the bond between O and CH3.]
- A. Hydroxyl
- B. hydroxyl and carbonyl
- C. Carboxyl and acetyl
- D. Carboxyl and ester
Answer, explanation and textbook page: open in the app.
11.Which of the four colligative properties arises in systems where there is an equilibrium between a liquid solution phase and a second liquid phase?
- A. Vapour pressure lowering
- B. Boiling point elevation
- C. Freezing point depression
- D. Osmotic pressure
Answer, explanation and textbook page: open in the app.
12.Which of the following can function as both a Brønsted-Lowry acid and Brønsted-Lowry base?
- A. H₂SO₄
- B. HSO₃⁻
- C. SO₄²⁻
- D. H⁺
Answer, explanation and textbook page: open in the app.
13.What makes the phosphorus cycle different from the carbon and nitrogen cycles?
- A. Phosphorus is found in the atmosphere in the gaseous state.
- B. Carbon and nitrogen are released at lower rate compared to phosphate salts.
- C. Phosphorus salts are released at higher rate compared to carbon and nitrogen cycles.
- D. Carbon and nitrogen are found in the atmosphere in the gaseous state.
Answer, explanation and textbook page: open in the app.
14.When Na₂CrO₄ solution is acidified, which of the following is formed?
- A. Cr (metal)
- B. Cr₂O₃
- C. CrO₄²⁻
- D. Cr₂O₇²⁻
Answer, explanation and textbook page: open in the app.
15.Nylon is a/an___?
- A. Amide
- B. Peptide
- C. Polyamide
- D. Polyester
Answer, explanation and textbook page: open in the app.
16.Which of the following is NOT a component of polysaccharides?
- A. Glucose
- B. Sucrose
- C. Cellulose
- D. Glycogen
Answer, explanation and textbook page: open in the app.
17.Which of the following is the SI measurement unit of electric current?
- A. Ampere
- B. Watt
- C. Volt
- D. Coulomb
Answer, explanation and textbook page: open in the app.
18.What is the first step in a scientific investigation?
- A. Ask questions
- B. Make observations
- C. Do research
- D. Draw conclusions
Answer, explanation and textbook page: open in the app.
19.In the electromagnetic spectrum with wavelengths shown (in micrometers, m), which bracketed section of the μ spectrum represents visible light? μm [Figure: A horizontal axis labeled 'wavelength ( )' with tick marks at 0.2, 0.4, 0.6, 0.8, 1, 2, 4, 8, 10, 12, and 20. μm μm μm μm Above the axis are four curly brackets indicating intervals: bracket 'x' spans from 0.4 to 0.8 ; bracket 'y' spans from 0.8 to 4 ; bracket 'z' spans from 4 to 12 ; bracket 'o' spans from 12 to 20 .]
- A. o
- B. x
- C. y
- D. z
Answer, explanation and textbook page: open in the app.
20.Which of the orbitals in the figure below has (have) an angular momentum quantum number of $\ell=2$? [Figure: Four electron density cross-section diagrams labeled I, II, III, and IV. I and III are spherically symmetric showing concentric circular rings (s orbitals). II shows a four-lobed cloverleaf pattern (d orbital). IV shows two vertically aligned lobes with a nodal plane between them (p orbital).]
- A. I
- B. I and III
- C. II
- D. I and IV
Answer, explanation and textbook page: open in the app.
21.Which groups in the periodic table form ionic bonds?
- A. Groups 1(1A) & 7(7B), Groups 2(2A) & 6(6B)
- B. Groups 1(1A) & 17(7A), Groups 2 (2A) & 16(6A)
- C. Groups 1(1A) & 18(8A), Groups 4(4B)& 14 (4A)
- D. Groups 3(3B) & 5(5B), Groups 4(4B) & 14 (4A)
Answer, explanation and textbook page: open in the app.
22.There is a progressive decrease in the bond angle in the series of molecules CCl₄, PCl₃, and H₂O. According to the VSEPR model, this is best explained by:
- A. Increasing electronegativity of the central atom
- B. Increasing number of lone pair electrons
- C. Decreasing size of the central atom
- D. Decreasing bond strength
Answer, explanation and textbook page: open in the app.
23.For the reaction $\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}$, the rate of disappearance of $\mathrm{H_2}$ is $0.01\,\mathrm{mol\,L^{-1}\,min^{-1}}$. What is the rate of appearance of $\mathrm{NH_3}$?
- A. $0.01\,\mathrm{mol\,L^{-1}\,min^{-1}}$
- B. $0.02\,\mathrm{mol\,L^{-1}\,min^{-1}}$
- C. $0.007\,\mathrm{mol\,L^{-1}\,min^{-1}}$
- D. $0.002\,\mathrm{mol\,L^{-1}\,min^{-1}}$
Answer, explanation and textbook page: open in the app.
24.The appropriate unit for a first order rate constant are?
- A. $\mathrm{M/s}$
- B. $1/\mathrm{M}\ \mathrm{s}$
- C. $1/\mathrm{M^2}\ \mathrm{s}$
- D. $1/\mathrm{s}$
Answer, explanation and textbook page: open in the app.
25.$2\mathrm{X}_{(g)} \rightleftharpoons 3\mathrm{Y}_{(g)} + \mathrm{Z}_{(g)}\quad \Delta H_{(\text{forward rxn})}>0$ The molar equilibrium concentrations for the reaction mixture represented above at 298 K are $[\mathrm{X}] = 4.0\,\mathrm{M}$, $[\mathrm{Y}] = 5.0\,\mathrm{M}$, and $[\mathrm{Z}] = 2.0\,\mathrm{M}$. What is the value of the equilibrium constant, $K_{eq}$, for the reaction at 298 K?
- A. 0.06
- B. 2.50
- C. 16.0
- D. 62.5
Answer, explanation and textbook page: open in the app.
26.What is the IUPAC name for the following carboxylic acid?
- A. 3,3-dimethylbutanoic acid
- B. 2-methylpentanoic acid
- C. 2,2-dimethylbutanoic acid
- D. 3-methylpentanoic acid
Answer, explanation and textbook page: open in the app.
27.4 L of 0.02 M of aqueous solution of NaCl is diluted with 1 L of water. What is the molarity of the solution?
- A. 0.004
- B. 0.008
- C. 0.012
- D. 0.016
Answer, explanation and textbook page: open in the app.
28.How much water, in liters, must be added to 0.50 liter of 6.0 M HCl to make the solution 2.0 M?
- A. 0.50
- B. 1.0
- C. 1.5
- D. 2.0
Answer, explanation and textbook page: open in the app.
29.What is the pH of a 0.10 M solution of NH₃, a weak base, whose ?
- A. 2.89
- B. 4.76
- C. 9.24
- D. 11.11
Answer, explanation and textbook page: open in the app.
30.Which of the following is the correct reaction taking place at the electrodes during the electrolysis of dilute sodium chloride solution?
- A. Anode: 2 Cl⁻(aq) → Cl₂ (l) + 2e⁻ Cathode: 2 Na⁺ (aq) + 2e- → 2 Na (s)
- B. Anode: 2 H₂O (l) → O₂ (g) + 4 H⁺ (aq) + 4e⁻ Cathode: 2 H₂O (l) + 2 e⁻ → H₂ (g) + OH⁻(aq)
- C. Anode: 2 Cl⁻ (aq) → Cl₂ (l) + 2e⁻ Cathode: 2 H₂O (l) + 2 e⁻ → H₂ (g) + OH⁻(aq)
- D. Anode: 2 H₂O (l) → O₂ (g) + 4 H⁺ (aq) + 4e⁻ Cathode: 2 Na⁺ (aq) + 2e- → 2 Na (s)
Answer, explanation and textbook page: open in the app.
31.Precision refers to _________
- A. how close a measured number is to the true value
- B. how close a measured number is to zero
- C. how close a measured number is to other measured numbers
- D. how close a measured number is to the calculated value
Answer, explanation and textbook page: open in the app.
32.Consider the following two possibilities for electron transfer in a hydrogen atom, given below: First: The electron drops from the Bohr orbit n = 3 to the orbit n = 2, followed by the transition from n = 2 to n = 1 Second: The electron drops from the Bohr orbit n = 3 directly to the orbit n = 1 Which of the following is correct about the energy change of these transitions?
- A. The sum of the energies for the first transitions is less than the energy of transition of the second.
- B. The sum of the energies for the first transitions is equal to the energy of transition of the second.
- C. The sum of the energies for the first transitions is greater than the energy of transition of the second.
- D. The energies of transitions of the first and the energy of transition of the second can't be compared.
Answer, explanation and textbook page: open in the app.
33.Which of the following elements has the highest fifth ionization energy (IE₅)?
- A. Al
- B. Si
- C. P
- D. S
Answer, explanation and textbook page: open in the app.
34.Which one of the following type of bonding exists between atoms with very different electro-negativities?
- A. Metallic bonding
- B. Hydrogen bonding
- C. Network covalent bonding
- D. Ionic bonding
Answer, explanation and textbook page: open in the app.
35.Which one of the following reactions at equilibrium would be unaffected by an increase in pressure? (I) N₂ (g) + ⇌ ⇌ ⇌ ⇌ 3H₂ (g) 2NH₃ (g) (II) 2H₂ (g) + O₂ (g) 2H₂O (g) (III) N₂ (g) + O₂ (g) 2NO (g) (IV) 2CO (g) + O₂ (g) 2CO₂ (g)
- A. I
- B. II
- C. III
- D. IV
Answer, explanation and textbook page: open in the app.
36.A sealed isothermal container initially contained 2 moles of CO gas and 3 moles of H₂ gas. The following reversible reaction occurred: ⇌ CO(g) + 2 H₂(g) CH₃OH(g) At equilibrium, there was 1 mole of CH₃OH in the container. What was the total number of moles of gas present in the container at equilibrium?
- A. 1
- B. 2
- C. 4
- D. 3
Answer, explanation and textbook page: open in the app.
37.Hydrolysis of ester leads to the formation of which of the following products in basic medium?
- A. Ether and alcohol
- B. Aldehyde and alcohol
- C. Alcohol and sodium carboxylate
- D. Sodium carboxylate
Answer, explanation and textbook page: open in the app.
38.When a saturated solution of sodium chloride is heated, it becomes
- A. Unsaturated
- B. Remains saturated
- C. Supersaturated
- D. Attains equilibrium conditions
Answer, explanation and textbook page: open in the app.
39.The pH of a solution prepared by the addition of 100 mL 0.002 M HCl to 100-mL distilled water is closest to:
- A. 1.0
- B. 1.5
- C. 2.0
- D. 3.0
Answer, explanation and textbook page: open in the app.
40.A chemist creates a buffer solution by mixing equal volumes of a 0.2-molar HOCl solution and a 0.2-molar KOCl solution. Which of the following will occur when a small amount of KOH is added to the solution? I. The concentration of undissociated HOCl will increase. II. The concentration of OCl⁻ ions will increase. III. The concentration of H⁺ ions will increase.
- A. I only
- B. II only
- C. III only
- D. I and III only
Answer, explanation and textbook page: open in the app.
41.Based on the information given in the table below, what is the enthalpy change for the reaction: $2\,\mathrm{H_2O_2(g)} + \mathrm{S(s)} \rightarrow \mathrm{SO_2(g)} + 2\,\mathrm{H_2O(g)}$ A table with two columns and four data rows: Header: 'Substance' and '$\Delta H_f^\circ$ (kJ/mol)': $\mathrm{H_2O_2(g)}$ | −150 $\mathrm{SO_2(g)}$ | −300 $\mathrm{H_2O(g)}$ | −250 $\mathrm{S(s)}$ | 0
- A. −500 kJ
- B. −200 kJ
- C. 200 kJ
- D. 400 kJ
Answer, explanation and textbook page: open in the app.
42.Features common to both galvanic and electrolytic cells include which of the following? I. Oxidation at the anode II. Can perform electrolysis III. Spontaneous
- A. I only
- B. II only
- C. III only
- D. I and II only
Answer, explanation and textbook page: open in the app.
43.Which of the following reactions is NOT involved in the contact process, during the production of sulfuric acid?
- A. SO₂ + O₂ 2 SO₃
- B. SO₃ + H₂O H₂SO₄ → → → →
- C. SO₃ + H₂SO₄ H₂S₂O₇
- D. H₂S₂O₇ + H₂O H₂SO₄
Answer, explanation and textbook page: open in the app.
44.Two types of polymer are shown below. Which of the following statements concerning these polymers is correct? [Figure: Two schematic drawings of polymer structures labeled X and Y. Diagram X shows three horizontal wavy polymer chains with vertical dashed lines representing weak intermolecular attractions between adjacent chains. Diagram Y shows three horizontal polymer chains connected to each other by solid vertical and angled covalent cross-links, forming a continuous network.]
- A. X and Y are thermosetting
- B. X is thermosetting and Y is thermoplastic
- C. X is thermoplastic whereas Y is thermosetting
- D. X and Y are thermoplastic
Answer, explanation and textbook page: open in the app.
45.The energy of an electron in the first Bohr orbit of hydrogen atom is -13.6 eV. The possible value of the excited state for electron in Bohr orbits of hydrogen is_______.
- A. -1.51 eV
- B. -6.8 eV
- C. -4.21 eV
- D. +6.8 eV
Answer, explanation and textbook page: open in the app.
46.The sublevel that can be occupied by a maximum of 10 electrons is identified by the letter________.
- A. d
- B. f
- C. p
- D. s
Answer, explanation and textbook page: open in the app.
47.What is the molecular shape of $\mathrm{ICl_4^-}$?
- A. Octahedral
- B. T-shaped
- C. Square planar
- D. Trigonal bipyramidal
Answer, explanation and textbook page: open in the app.
48.What hybridization change, if any, occurs at the underlined atom in the following reaction: $\underline{\mathrm{C}}\mathrm{O_2}+\mathrm{H_2O}\to\mathrm{H_2CO_3}$
- A. $sp\to sp^2$
- B. $sp^3\to sp^3d$
- C. $sp^2\to sp^3$
- D. No hybridization change observed
Answer, explanation and textbook page: open in the app.
49.The proposed reaction mechanism between nitrogen monoxide and bromine is give below. $\mathrm{NO}+\mathrm{Br_2}\rightleftharpoons\mathrm{NOBr_2}\ \text{(fast)}$ $\mathrm{NOBr_2}+\mathrm{NO}\to2\mathrm{NOBr}\ \text{(slow)}$ Which of the following rate equations is consistent with the proposed mechanism?
- A. Rate = $k\,[\mathrm{NO}]^2$
- B. Rate = $k\,[\mathrm{NO}][\mathrm{Br_2}]^2$
- C. Rate = $k\,[\mathrm{NO}][\mathrm{Br_2}]$
- D. Rate = $k\,[\mathrm{NO}]^2[\mathrm{Br_2}]$
Answer, explanation and textbook page: open in the app.
50.Which one of the following statements regarding a dynamic equilibrium is FALSE?
- A. At equilibrium, there is no net change in the system.
- B. At equilibrium, the forward and reverse reactions cease to occur.
- C. At equilibrium, the rates of the forward and back reactions are identical.
- D. At equilibrium, the concentration of reactants and products stays the same.
Answer, explanation and textbook page: open in the app.
51.In which of the following cases will the dissolution of sugar be the most rapid?
- A. Sugar crystals in hot water.
- B. Powdered sugar in hot water.
- C. Sugar crystals in cold water
- D. Powdered sugar in cold water.
Answer, explanation and textbook page: open in the app.
52.If a solution of acetic acid (CH₃COOH) has a pH of 3.00, what is its concentration? Ka of acetic acid =
- A. 0.0057 M
- B. 0.057 M
- C. 0.57 M
- D. 5.70 M
Answer, explanation and textbook page: open in the app.
53.The indicator methyl red is red in a solution of NaH₂PO₄. Which of the following equations is consistent with this observation?
- A. H₂PO₄⁻ + H₂O H₃PO₄ + OH⁻
- B. H₂PO₄⁻ + H₂O HPO₄²⁻ + H₃O⁺ ⇌ ⇌ ⇌ ⇌
- C. HPO₄²⁻ + H₂O PO₄³⁻ + H₃O⁺
- D. HPO₄²⁻ + H₂O H₂PO₄⁻ + OH⁻
Answer, explanation and textbook page: open in the app.
54.A nickel electrode can undergo oxidation to Ni²⁺ ion as follows: → ∘ → ∘ Ni (s) Ni²⁺ (aq) + 2e⁻ E red= -0.28 V 2H₂O(l) 4H⁺ (aq) +O₂(g) +4e⁻ E red= 1.23 V What will happen during the electrolysis of concentrated aqueous solution of NiSO₄ using Ni electrodes? (I)Nickel will deposit at the cathode. (II)Nickel will dissolve at the anode. (III)Oxygen will be released at the anode. (IV)Nickel will deposit at the anode.
- A. I only
- B. I,II
- C. I,III
- D. II, IV
Answer, explanation and textbook page: open in the app.
55.Which of the following is NOT true about the photoelectric effect?
- A. Most metals require ultraviolet light to emit electrons.
- B. A bright light causes more electrons to be emitted than a weak light.
- C. Higher frequency light emits electrons with higher kinetic energy
- D. A bright light causes less electrons to be emitted than a weak light.
Answer, explanation and textbook page: open in the app.
56.Which of the following statements is correct about nitrosyl chloride (NOCl)?
- A. It has a bent or angular geometry with N a central atom.
- B. It has a bent or angular geometry with O a central atom.
- C. It has a trigonal planar geometry with N a central atom.
- D. It has a trigonal planar geometry with O a central atom.
Answer, explanation and textbook page: open in the app.
57.The minimum energy required for an effective collision is called______.
- A. potential energy
- B. activation energy
- C. free energy
- D. kinetic energy
Answer, explanation and textbook page: open in the app.
58.A sample of solid ammonium carbamate is heated in a closed container at 298 K and allowed to reach equilibrium. $\mathrm{NH_4CO_2NH_2\ (s) \rightleftharpoons 2\ NH_3\ (g) + CO_2\ (g)}$ If the total pressure of the system is 0.114 atm, what is the value of equilibrium constant, $K_p$?
- A. $1.29 \times 10^{-3}$
- B. $3.80 \times 10^{-4}$
- C. $7.60 \times 10^{-3}$
- D. $2.19 \times 10^{-4}$
Answer, explanation and textbook page: open in the app.
59.During esterfication of carboxylic acid with alcohol which bond of carboxylic acid undergoes cleavage?
- A. C - C
- B. C = O
- C. C - O
- D. O - H
Answer, explanation and textbook page: open in the app.
60.If 49 grams of H₂SO₄ react with 80.0 grams of NaOH, how much reactant will be left over after the reaction is complete?
- A. 24.5 g H₂SO₄
- B. 20.0 g NaOH
- C. 40.0 g NaOH
- D. 60.0 g NaOH
Answer, explanation and textbook page: open in the app.
61.What is the change in internal energy of a system that releases 12.4 J of heat and does 4.2 J of work on the surroundings
- A. 16.6 J
- B. 8.2 J
- C. -16.6 J
- D. -8.2 J
Answer, explanation and textbook page: open in the app.
62.Which one of the following is true?
- A. Entropy increases when a liquid freezes at its melting point.
- B. For spontaneous process . ΔS > 0
- C. For a spontaneous process . ΔG > 0
- D. Entropy of the pure crystalline solid is zero at 0°C.
Answer, explanation and textbook page: open in the app.
63.Which of the following has the same number of significant figures as the number 1.00310? 106
- A. 100
- B. 1 ×
- C. 199.791
- D. 5.119
Answer, explanation and textbook page: open in the app.
64.When an electron in a hydrogen atom makes the transition from the $n=4$ state to the $n=2$ state, blue light with a wavelength of 434 nm is emitted. Which of the following expressions gives the energy released by the transition?
- A. $\frac{(6.63\times10^{-34})(3.00\times10^8)}{(4.34\times10^{-7})}$ joules
- B. $\frac{(6.63\times10^{-34})}{(4.34\times10^{-7})(3.00\times10^8)}$ joules
- C. $\frac{(6.63\times10^{-34})(4.34\times10^{-7})}{(3.00\times10^8)}$ joules
- D. $\frac{(4.34\times10^{-7})}{(6.63\times10^{-34})(3.00\times10^8)}$ joules
Answer, explanation and textbook page: open in the app.
65.Arrange the following molecules in the order of increasing stability.
- A. N₂⁺ < N₂ < N₂⁻ < N₂²⁻
- B. N₂²⁻ < N₂⁻ = N₂⁺ < N₂
- C. N₂²⁻ < N₂⁻ < N₂ < N₂⁺
- D. N₂ < N₂⁺ = N₂⁻ < N₂²⁻
Answer, explanation and textbook page: open in the app.
66.The reaction below takes place with all of the reactants and products in the gaseous phase. Which of the following is true of the relative rates of disappearance the reactants and appearance of the products? 2 NOCl → 2 NO + Cl₂
- A. NO appears at twice the rate that NOCl disappears.
- B. Cl₂ appears at the same rate that NOCl disappears.
- C. NO appears at half the rate that NOCl disappears.
- D. NO appears at the same rate that NOCl disappears.
Answer, explanation and textbook page: open in the app.

In the Figure shown below, what does O denote? [Figure: A phase diagram plotting pressure on the vertical axis (with values 0.1, 1, and 100 marked) against temperature on the horizontal axis. The diagram is divided into three phase regions: "Solid" on the left, "Liquid" in the upper central region, and "Vapour" on the lower right. Three boundary curves meet at a single intersection point labeled "O": a sublimation curve rising from the origin to point O, a solid-liquid boundary curve with a negative slope extending upward to label B, and a liquid-vapour curve rising to the right toward point A. Dashed horizontal and vertical reference lines connect point O to the pressure value 0.1 and the temperature axis, respectively.

67.Another horizontal dashed line at pressure 1 intersects the solid-liquid line and liquid-vapour line, with vertical dashed lines dropping to the temperature axis.]
- A. Melting point
- B. Triple point
- C. Boiling point
- D. Vaporization point
Answer, explanation and textbook page: open in the app.
68.Given the following unbalanced equation How many grams of are needed to make 250 mL of 0.20 N solution?
- A. 3.95 g
- B. 3.16 g
- C. 2.98 g
- D. 1.58 g
Answer, explanation and textbook page: open in the app.
69.Consider the following equilibria: (I) (II) (III) In which of the equilibrium ( equilibria) does water act as a Brønsted-Lowry base?
- A. I only
- B. II only
- C. II and III
- D. I, II, III
Answer, explanation and textbook page: open in the app.
70.A certain current produces 0.50 g of hydrogen gas in 2.0 hrs. What is the amount of copper librated from a solution of copper sulfate by the same current flowing for the same time?
- A. 31.8 g
- B. 63.6 g
- C. 15.9 g
- D. 6.36 g
Answer, explanation and textbook page: open in the app.
71.For which of the following half-cells is the reduction potential E independent of the pH of the solution?
- A. [Cr₂O₇]²⁻ + 14H⁺+6e⁻ ⇄ 2Cr³⁺ + 7H₂O
- B. H₂O₂ + 2H⁺+2e⁻ ⇄ 2H₂O
- C. [NO₃]⁻+H₂O +2e⁻ ⇄ [NO₂]⁻ + 2[OH]⁻
- D. Co²⁺ + 2e⁻ ⇄ Co
Answer, explanation and textbook page: open in the app.
72.What is the basis for the Scientific Method?
- A. To formulate a research problem, test the hypothesis under carefully controlled conditions that challenge the hypothesis
- B. To test hypotheses and if they are disproved, they should be abandoned completely.
- C. To test hypotheses in conditions that are favourable to their success.
- D. To formulate a research problem and disprove the hypothesis.
Answer, explanation and textbook page: open in the app.
73.Which of the following molecules has the largest dipole moment?
- A. CO
- B. HCN
- C. HCl
- D. HF
Answer, explanation and textbook page: open in the app.
74.In three different experiments the following results were obtained for the reaction A → products: [A]ₒ = 1.00 M, t₁/₂ = 50 min; [A]ₒ = 2.00 M, t₁/₂ = 25 min; [A]ₒ = 0.50 M, t₁/₂ = 100 min. What is the value of the rate constant for this reaction? 0.010 L mol min −1 −1 0.020 L mol min −1 −1
- B. 0.030 L mol min −1 −1 0.040 L mol min −1 −1
Answer, explanation and textbook page: open in the app.
75.Which of the following compounds is the least soluble in water?
- A. (NH₄)₂CO₃
- B. BaCO₃
- C. Fe(NO₃)₃
- D. Na₃(PO₄)
Answer, explanation and textbook page: open in the app.
76.What is the freezing point of a solution of 250 g of $\mathrm{CaCl_2}$ in 1.0 kg of water? ($K_f$ for $\mathrm{H_2O}$ = 1.86 kg/mol)
- A. - 1.3 °C
- B. - 6.5 °C
- C. - 9.0 °C
- D. - 13 °C
Answer, explanation and textbook page: open in the app.
77.Which of the following metals cannot be electroplated on to the surface of another metal using an aqueous E∘ E∘ E∘ E∘ electrolyte? (Ni²⁺/Ni) = -0.28 V; (Cu²⁺/Cu) = 0.34 V, (Mg ²⁺/Mg) = -2.37 V; (Ag ⁺/Ag) = 0.80 V
- A. Ni
- B. Cu
- C. Mg
- D. Ag
Answer, explanation and textbook page: open in the app.

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