Deck 15: Solutions of Acids and Bases

Question 1

Which of the following is a property of an acid?
I. Slippery to touch.
II. Tastes sour.
III. Reacts with active metals to form H₂ gas.

A) I only
B) II only
C) I and II
D) II and III
E) All of these

Answer 1

II and III

Question 2

What is the conjugate acid of the species H₂BO₃^{1 -} ?

A) H₃BO₃
B) H₃BO₃^{2 -}
C) H₃O⁺
D) HBO₃^{2 -}
E) HBO₃

Answer 2

H₃BO₃

Question 3

For the reaction CN - (aq) + H₂ O ( ) HCN (aq) + OH - (aq), one of the acid-base conjugate pairs is:

A) HCN, H₂O
B) HCN, CN ^-
C) H₂O, CN ^-
D) HCN, OH ^-
E) CN ^- , OH ^-

Answer 3

HCN, CN ^-

Question 4

Which of the following is a property of a base?
I. Slippery to touch.
II. Tastes bitter.
III. Reacts with active metals to form H₂ gas.

A) I only
B) II only
C) I and II
D) II and III
E) All of these

Question 5

Consider the following Bronsted-Lowery acid-base reaction:
HClO ₂ + N(CH ₃) ₃ HN(CH ₃) ₃+ + ClO ₂ 1 -Which two substances represent Bronsted-Lowery bases in this reaction?

A) HClO₂ and N(CH₃)₃
B) HClO₂ and [HN(CH₃)₃]⁺
C) N(CH₃)₃ and [HN(CH₃)₃]⁺
D) N(CH₃)₃ and ClO₂^{1 -}
E) [HN(CH₃)₃]⁺ and ClO₂^{1 -}

Question 6

What is the conjugate acid of HSO₄^{1 -} ?

A) H₂SO₄
B) H₂SO₄^{2 -}
C) SO₄
D) SO₄^{2 -}
E) H₃O⁺

Question 7

In the unusual acid-base reaction HClO₄ + H₂ SO₄ ClO₄- + H ₃SO₄+ , one of the conjugate acid-base pairs is:

A) HClO₄, H₂SO₄
B) H₂SO₄, ClO₄ ^-
C) ClO₄ ^- , H₃SO₄⁺
D) H₃SO₄⁺, H₂SO₄
E) HClO₄, H₃SO₄⁺

Question 8

Which aqueous solution(s) below is(are) considered basic ?
I. A solution with a pH = 6
II. A solution with [OH ^- ] = 1×10 ^{- 7}
III. A solution with [H₃O⁺] = 1×10 ^{- 9}

A) I only
B) II only
C) III only
D) I and II
E) I and III

Question 9

Which of the following aqueous solutions is(are) considered basic ?
I. [H₃O⁺] = 5.4×10 ^{- 8} M
II. pOH = 9.0
III. [OH ^- ] = 4.3×10 ^{- 4}

A) I only
B) I and II
C) I and III
D) II and III
E) All of these

Question 10

What is the conjugate acid of HBO₃^{2 -} ?

A) H₃BO₃
B) H₂BO₃^{1 -}
C) H₂BO₃^{3 -}
D) BO₃^{3 -}
E) BO₃^{1 -}

Question 11

Which species listed below is the conjugate base of NH₃?

A) NH₄⁺
B) NH₄
C) NH₂¹⁺
D) NH₂^{1 -}
E) OH ^-

Question 12

The conjugate acid of HPO₄^{2 -} is:

A) H₃PO₄
B) H₂PO₄ ^-
C) PO₄^{3 -}
D) H⁺
E) none of these

Question 13

In the reaction:
N₂H₄ (aq) + H₂ O N₂H₅ + (aq) + OH - (aq)

A) N₂H₄ and N₂H₅⁺ act as acids.
B) H₂O and N₂H₅⁺ act as acids.
C) N₂H₅⁺ and OH ^- act as acids.
D) only OH ^- acts as a base.
E) none of these.

Question 14

Consider the following Bronsted-Lowry acid-base reaction:
C₆H₅NH₂ + HCOOH→C₆H₅NH₃⁺ + HCOO ^- Which of the following is a conjugate acid-base pair?

A) C₆H₅NH₂ and HCO₂H
B) HCOOH and C₆H₅NH₃⁺
C) HCOO ^- and C₆H₅NH₂
D) C₆H₅NH₃⁺ and C₆H₅NH₂
E) C₆H₅NH₃⁺ and HCOO ^-

Question 15

At 37 ° C the autoionization constant of water is K _w = 2.4×10 ^{- 14}. What is the pH of pure water at 37 ° C?

A) 6.81
B) 7.00
C) 7.19
D) 2.39
E) 11.61

Question 16

A Bronsted-Lowry acid is

A) a proton acceptor.
B) an electron acceptor.
C) an electron donor.
D) a binary hydride.
E) a proton donor

Question 17

What is the conjugate acid of the species, HAsO₄^{2 -} ?

A) H₃O⁺
B) H₃AsO₄
C) H₂AsO₄^{1 -}
D) H₂AsO₄^{3 -}
E) AsO₄^{3 -}

Question 18

In the acid-base equilibrium PO₄ 3 - + NH ₄+ HPO₃ 2 - + NH₃, one conjugate acid-base pair is:

A) PO₄^{3 -} , NH₄⁺
B) NH₄⁺ , HPO₄^{2 -}
C) HPO₄^{2 -} , NH₃
D) NH₄⁺ , NH₃
E) none of these

Question 19

If the reaction below proceeds, which of the following is true?
NH₃ + C₂H₅OH→NH₂ ^- + C₂H₅OH₂⁺

A) C₂H₅OH is an acid.
B) NH₂ ^- is the conjugate base of NH₃.
C) NH₃ is a base.
D) C₂H₅OH₂⁺ is a base.
E) none of these

Question 20

Which of the following aqueous solutions is(are) considered acidic ?
I. pOH = 12.0
II. [H₃O⁺] = 4.2×10 ^{- 9}
III. [OH ^- ] = 5.3×10 ^{- 10}

A) II only
B) I and II
C) I and III
D) II and III
E) All of these

Question 21

From the information given below which one of the 5 solutions would be the most acidic?

A) pH = 6
B) pOH = 9
C) [H₃O⁺] = 10 ^{- 3} M
D) [OH ^- ] = 10 ^{- 10}
E) pOH = 12

Question 22

The pH of a certain black coffee is 5.3. What is its hydroxide ion concentration, [OH ^- ]?

A) 2.0×10 ^{- 9} M
B) 5.0×10 ^{- 6} M
C) 8.7 M
D) 2.0×10⁵ M
E) 5.0×10⁸ M

Question 23

Exhibit 15-2 The pH of a solution of a certain brand of Cola is 2.27. Use this information to solve the following problem(s).
Refer to Exhibit 15-2. What is the hydroxide ion concentration, [OH ^- ], of this solution?

A) 9.68×10 ^{- 14} M
B) 1.86×10 ^{- 12} M
C) 5.37×10 ^{- 3} M
D) 1.03×10 ^{- 1} M
E) 5.37×10¹¹ M

Question 24

What is the H₃O⁺ ion concentration in an aqueous solution having an OH ^- concentration of 1.0×10 ^{- 2} M?

A) 1.0×10 ^{- 2} M
B) 13×10 ^{- 2} M
C) 12×10 ^{- 2} M
D) 1.0×10 ^{- 12} M
E) 12×10 ^{- 12} M

Question 25

Which of the following aqueous solutions is(are) considered basic ?
I. [H₃O⁺] = 3.4×10 ^{- 10} M
II. pH = 8.54
III. [OH ^- ] = 6.7×10 ^{- 4} M

A) III only
B) I and II
C) I and III
D) II and III
E) All of these

Question 26

Which of the following aqueous solutions is(are) considered acidic ?
I. A solution with [OH ^- ] = 2.5×10 ^{- 8}
II. A solution with [H₃O⁺] = 1×10 ^{- 7}
III. A solution with a pOH = 8

A) I only
B) II only
C) III only
D) I and II
E) I and III

Question 27

The pH of a diet Coca Cola solution is 3.12. What is the concentration of [OH ^- ] present in this solution?

A) [OH ^- ] = 1.3×10 ^{- 25} M
B) [OH ^- ] = 7.6×10 ^{- 18} M
C) [OH ^- ] = 1.3×10 ^{- 11} M
D) [OH ^- ] = 7.6×10 ^{- 4} M
E) [OH ^- ] = 7.6×10¹⁰ M

Question 28

A solution is found to have a pH of 10.45. What is [H₃O⁺]?

A) 2.9×10 ^{- 5} M
B) 1.0 M
C) 2.8×10 ^{- 10} M
D) 3.5×10 ^{- 11} M
E) cannot be calculated from the information given

Question 29

The pH of a vinegar solution is 2.32. What is the hydronium ion concentration, [H₃O⁺], for this solution?

A) [H₃O⁺] = 2.1×10 ^{- 12} M
B) [H₃O⁺] = 4.8×10 ^{- 3} M
C) [H₃O⁺] = 0.36 M
D) [H₃O⁺] = 2.3 M
E) [H₃O⁺] = 2.1×10² M

Question 30

Exhibit 15-1 The pH of a certain brand of milk is 6.60. Use this information to answer the following question(s).
Refer to Exhibit 15-1. What is the molar concentration of the hydronium ion , [H₃O⁺], in this milk?

A) 2.5×10 ^{- 7} M
B) 6.0×10 ^{- 6} M
C) 6.6×10 ^{- 1} M
D) 8.2×10 ^{- 1} M
E) 4.0×10⁶ M

Question 31

Measurements show that the [OH ^- ] of a solution is 6.02×10 ^{- 6} M. The pH of this solution is:

A) 8.78
B) 5.22
C) 6.02
D) 9.78
E) none of these

Question 32

The hydroxide ion concentration in a solution with pH = 3.50 is:

A) 3.2×10 ^{- 2} M
B) 3.2×10 ^{- 4} M
C) 3.2×10 ^{- 11} M
D) 3.2×10 ^{- 10} M
E) none of these

Question 33

The hydronium ion concentration, [H₃O⁺], for a certain brand of beer is 3.16×10 ^{- 5} M. What is the pOH of this aqueous solution?

A) pOH = 0.00; there can be no hydroxide ion present when hydronium ion is present.
B) pOH = 3.64
C) pOH = 4.50
D) pOH = 9.50
E) pOH = 10.36

Question 34

Exhibit 15-2 The pH of a solution of a certain brand of Cola is 2.27. Use this information to solve the following problem(s).
Refer to Exhibit 15-2. What is the pOH of this solution?

A) 0.99
B) 6.17
C) 11.73
D) 16.27
E) 27.01

Question 35

The pH of a solution is 5. The [H₃O⁺] and [OH ^- ] are:

A) 10 ^{- 5} and 10 ^{- 7} M, respectively.
B) 10 ^{- 5} and 10 ^{- 9} M, respectively.
C) 10 ^{- 9} and 10 ^{- 7} M, respectively.
D) 10 ^{- 9} and 10 ^{- 5} M, respectively.
E) none of these

Question 36

The pH of a certain specimen of urine is 4.8. What is the hydroxide ion concentration, [OH ^- ], of this solution?

A) [OH ^- ] = 1.6×10 ^{- 19} M
B) [OH ^- ] = 6.3×10 ^{- 10} M
C) [OH ^- ] = 1.6×10 ^{- 5} M
D) [OH ^- ] = 6.3×10⁴ M
E) [OH ^- ] = 1.6×10⁹ M

Question 37

If the pH of a solution is 4.40:

A) [H₃O⁺] = 4.0×10 ^{- 5} M
B) [H₃O⁺] = 2.5×10 ^{- 4} M
C) [OH ^- ] = 3.4×10 ^{- 9} M
D) [OH ^- ] = 2.5×10 ^{- 11} M
E) pOH = 18.80

Question 38

Which of the following aqueous solutions is(are) considered basic ?
I. [OH ^- ] = 6.2×10 ^{- 8}
II. [H₃O⁺] = 3.8×10 ^{- 12}
III. pOH = 2.5

A) I only
B) I and II
C) I and III
D) II and III
E) All of these

Question 39

Exhibit 15-1 The pH of a certain brand of milk is 6.60. Use this information to answer the following question(s).
Refer to Exhibit 15-1. What is the molar concentration of hydroxide ion , [OH ^- ], in this milk?

A) 2.5×10 ^{- 21} M
B) 1.2×10 ^{- 14} M
C) 1.5×10 ^{- 14} M
D) 1.7×10 ^{- 9} M
E) 4.0×10 ^{- 8} M

Question 40

A famous brand of sweet and sour barbecue sauce (consisting of tomato paste, water, vinegar, sugar, and secret spices) has a measured pH of 2.6. What is the hydrogen ion concentration in the sauce?

A) 0.42 M
B) 2.4×10 ^{- 2} M
C) 2.5×10 ^{- 3} M
D) 3.4×10 ^{- 4} M
E) 5×10 ^{- 5} M

Question 41

A solution of KOH is found to have [OH ^- ] = 0.010 M. What is the pH of this solution?

A) 14.0
B) 12.0
C) 2.0
D) 13.0
E) 1.0

Question 42

Which compound is a strong acid in water?

A) H₂SO₄
B) NH₃
C) HF
D) NaOH
E) none of these

Question 43

What is the Calcium hydroxide concentration, [Ca(OH)₂], of an aqueous Ca(OH)₂ solution with a pH = 9.60?

A) 1.3×10 ^{- 10} M
B) 2.5×10 ^{- 10} M
C) 2.0×10 ^{- 5} M
D) 4.0×10 ^{- 5} M
E) 8.0×10 ^{- 5} M

Question 44

Acid strengths are measured and compared how?

A) By measuring the concentration of the acid.
B) By measuring the pH of the aqueous solution.
C) By measuring the extent of ionization as determined by the reaction's K _a.
D) By measuring how corrosive the acid is.
E) All of these.

Question 45

What is the pH of 2.0 liters of aqueous solution that contains 9.0 grams of HCl?

A) 0.12
B) 0.660
C) 0.810
D) 0.90
E) 13.10

Question 46

What is the pH of 0.0040 M HCl ?

A) 3.61
B) 11.60
C) 10.63
D) 2.64
E) 2.40

Question 47

Which of the following is considered a strong acid when dissolved in water?

A) H₃PO₄
B) HF
C) H₂SO₄
D) HClO
E) All of these

Question 48

A nitric acid (HNO₃) solution is 16.2 M. Which of the following is correct?

A) pH = 1.21
B) pH = 2.78
C) pOH = 15.21
D) [OH ^- ] = 1.62×10¹⁵
E) must know K _a

Question 49

Which of the following acids is considered a strong acid when dissolved in water?
I. HNO₂ (Nitrous acid)
II. HClO₄ (Perchloric acid)
III. HF (Hydrofluoric acid)

A) I only
B) II only
C) III only
D) I and II
E) All of these

Question 50

What is the pOH of a 1.0×10 ^{- 4} M solution of HI?

A) 10.00
B) 4.00
C) 18.00
D) - 4.00
E) 2.00

Question 51

Which of the following is considered a weak acid when dissolved in water?
I. HNO₂
II. HF
III. H₂SO₃

A) I only
B) II only
C) III only
D) All of these
E) None of these

Question 52

What is the pH of an aqueous 3.3 M Ba(OH)₂ solution?

A) pH = - 0.51
B) pH = - 0.81
C) pH = 13.19
D) pH = 13.49
E) pH = 14.82

Question 53

Given the following Bronsted-Lowery acid-base reaction and its corresponding equilibrium constant, which substance is the strongest acid ?
CH ₃CH ₂ NH₃+ + ClO₂₁ - CH ₃CH ₂ NH₂ + HClO ₂ K = 2.1 10 - 9

A) CH₃CH₂NH₃⁺
B) ClO₂^{1 -}
C) CH₃CH₂NH₂
D) HClO₂

Question 54

A dilute solution of HBr is found to have a pH of 3.55. What is [H₃O⁺]?

A) 0.35 M
B) 3.8×10 ^{- 4} M
C) 2.8×10 ^{- 4} M
D) 5.5×10 ^{- 3} M
E) 3.2×10 ^{- 11} M

Question 55

What is the pH of 0.025 M Ba(OH)₂?

A) 0.050
B) 1.30
C) 12.70
D) 2×10 ^{- 13}
E) none of these

Question 56

What is the pH of a 2.6 M aqueous solution of Ba(OH)₂?

A) 7.94×10 ^{- 6}
B) 0.71
C) 13.29
D) 14.41
E) 14.72

Question 57

What is the pH of 3.9×10 ^{- 4} M HNO₃?

A) - 3.40
B) 0.03
C) 3.41
D) 3.51
E) none of these

Question 58

Which compound is a strong base in water?

A) H₂SO₄
B) NH₃
C) HF
D) NaOH
E) none of these

Question 59

Which of the following is considered a strong acid when dissolved in water?
I. HClO₂
II. HBr
III. HNO₃

A) I only
B) II only
C) II and III
D) All of these
E) None of these

Question 60

What is the pH of 1×10 ^{- 6} M HCl?

A) 6.00
B) 6.98
C) 7.98
D) 8.00
E) need K _a

Question 61

What is the H₃O⁺ concentration in a solution formed by dissolving 63 g of HNO₃ in 2.0 liters of water?
[molar mass of HNO₃ = 63 g/mol]

A) 1.0 M
B) 0.50 M
C) 0.050 M
D) 2.0 M
E) none of these

Question 62

Which base listed below would be the strongest given the corresponding acid ionization constants for their conjugate acids?

A) PO₄^{3 -} ; K _a(HPO₄^{1 -} ) = 4.2×10 ^{- 13}
B) NO₂^{1 -} ; K _a(HNO₂) = 7.1×10 ^{- 4}
C) HCO₃^{1 -} ; K _a(H₂CO₃) = 4.5×10 ^{- 7}
D) CH₃COO^{1 -} ; K _a(CH₃COOH) = 1.8×10 ^{- 5}
E) F ^- ; K _a(HF) = 6.8×10 ^{- 4}

Question 63

Consider the following unfinished table of weak acids with their corresponding
P K _a values and K _a values. Weak Acid p K _a K _a HNO₂ 3.35 -- HF -- 6.8×10 ^{- 4} HCN 9.31 --
Arrange these three acids in order of increasing acid strength .

A) (weakest) HNO₂ < HF < HCN (strongest)
B) (weakest) HNO₂ < HCN < HF (strongest)
C) (weakest) HCN < HF < HNO₂ (strongest)
D) (weakest) HCN < HNO₂ < HF (strongest)
E) (weakest) HF < HNO₂ < HCN (strongest)

Question 64

After completing the following unfinished Base Ionization table, what is the order of increasing base strength ?
Base K _b p K _b Bicarbonate ion, HCO₃ ^- 2.2×10 ^{- 8} Pyridine, C₅H₅N 8.77 Acetate ion, CH₃COO ^- 5.7×10 ^{- 10}

A) (weakest) Bicarbonate ion < Pyridine < Acetate ion (strongest)
B) (weakest) Bicarbonate ion < Acetate ion < Pyridine (strongest)
C) (weakest) Pyridine < Bicarbonate ion < Acetate ion (strongest)
D) (weakest) Acetate ion < Pyridine < Bicarbonate ion (strongest)
E) (weakest) Acetate ion < Bicarbonate ion < Pyridine (strongest)

Question 65

Milk of magnesia is essentially a saturated solution of Mg(OH)₂ ( K _sp = 8.9×10 ^{- 12}). What is the pH of a saturated Mg(OH)₂ solution?

A) 10.32
B) 5.52
C) 10.12
D) 10.42
E) >12.0

Question 66

What is the pH of 2.7 M Ba(OH)₂?

A) pH = - 0.726
B) pH = 0.425
C) pH = 5.32
D) pH = 13.27
E) pH = 14.73

Question 67

50 mL of 0.50 M NaOH is added to enough water to make 1.0 liter of solution. Calculate the pH.

A) 0.3
B) 1.6
C) 12.4
D) 12.7
E) 13.7

Question 68

What is the pH of a solution prepared by dissolving 0.28 grams of KOH in 250 mL of solution?
(molar mass KOH = 56.11 g/mol)

A) 1.70
B) 12.30
C) 2.00×10 ^{- 2}
D) 11.7
E) 5.0×10 ^{- 13}

Question 69

A weak acid

A) does not react with base
B) does not react with glass
C) does not burn skin
D) does not dissociate fully
E) does not pose a disposal problem

Question 70

Which anionic base listed below would be the strongest given the corresponding acid ionization constants for their conjugate acids?

A) F ^- ; K _a(HF) = 6.8×10 ^{- 4}
B) CH₃COO ^- ; K _a(CH₃COOH) = 1.8×10 ^{- 5}
C) IO₃^{1 -} ; K _a(HIO₃) = 1.6×10 ^{- 1}
D) NO₂^{1 -} ; K _a(HNO₂) = 7.1×10 ^{- 4}

Question 71

A 0.010 M solution of the strong acid HNO₃ is prepared. Which of the following statements is false ?

A) The acid is completely ionized.
B) The pH of the solution is 2.0.
C) The equilibrium [NO₃ ^- ] is approximately 0.010 M.
D) The aqueous NO₃ ^- ion is a very weak base.
E) The equilibrium [HNO₃] is approximately 0.010 M.

Question 72

What is the pH of a solution prepared by dissolving 0.13 grams of HI (molar mass HI = 127.9 g/mol) in 300 mL of solution?

A) 5.48
B) 2.47
C) 0.37
D) 3.37
E) not enough information is given

Question 73

Rank the following three acids in terms of acid strength given the following information:
Acid K _a p K _a HF 6.9×10 ^{- 4} -- CH₃COOH -- 4.74 HNO₂ 4.5×10 ^{- 4}

A) (weakest acid) HF < CH₃COOH < HNO₂ (strongest acid)
B) (weakest acid) CH₃COOH < HNO₂ < HF (strongest acid)
C) (weakest acid) HNO₂ < HF < CH₃COOH (strongest acid)
D) (weakest acid) HF < HNO₂ < CH₃COOH (strongest acid)
E) (weakest acid) HNO₂ < CH₃COOH < HF (strongest acid)

Question 74

According to the definition of pH, what would be the pH of a 10 M solution of HCl?

A) 1
B) 0
C) - 1
D) 0.30
E) - 0.30

Question 75

What is the pH of a 1.6 M aqueous solution of Sr(OH)₂?

A) pH = - 0.49
B) pH = 12.87
C) pH = 13.81
D) pH = 14.19
E) pH = 14.50

Question 76

Consider the following unfinished table of weak acids with their corresponding p K _a values and K _a values. Weak Acid p K _a K _a Benzoic acid 4.20 -- Lactic acid -- 1.4×10 ^{- 4} Chlorous acid 1.96 -- Arrange these three acids in order of increasing acid strength .

A) (weakest) Benzoic acid < Lactic acid < Chlorous acid (strongest)
B) (weakest) Benzoic acid < Chlorous acid < Lactic acid (strongest)
C) (weakest) Lactic acid < Benzoic acid < Chlorous acid (strongest)
D) (weakest) Lactic acid < Chlorous acid < Benzoic acid (strongest)
E) (weakest) Chlorous acid < Benzoic acid < Lactic acid (strongest)

Question 77

Calculate the pOH of a solution made by dissolving 2.0 grams of NaOH (molar mass = 40.0 g/mol) in water and diluting tO₅ 00 mL.

A) 1.00
B) 13.00
C) 1.12
D) 1.30
E) 12.70

Question 78

Which acid listed below would be the strongest given the corresponding base ionization constants for their conjugate bases?

A) H₃PO₄; K _b(H₂PO₄^{1 -} ) = 1.4×10 ^{- 12}
B) H₂S; K _b(HS ^- ) = 1.1×10 ^{- 7}
C) HClO₂; K _b(ClO₂ ^- ) = 9.1×10 ^{- 13}
D) HNO₂; K _b(NO₂ ^- ) = 1.4×10 ^{- 11}
E) HIO; K _b(IO ^- ) = 4.3×10 ^{- 4}

Question 79

After completing the following unfinished table, what is the order of increasing base strength ?
Base K _b p K _b Fluoride ion, F ^- 1.5×10 ^{- 11} Ammonia, NH₃ 4.75 Acetate ion, CH₃COO ^- 5.7×10 ^{- 10}

A) (weakest) Fluoride ion < Ammonia < Acetate ion (strongest)
B) (weakest) Fluoride ion < Acetate ion < Ammonia (strongest)
C) (weakest) Ammonia < Fluoride ion < Acetate ion (strongest)
D) (weakest) Acetate ion < Ammonia < Fluoride ion (strongest)
E) (weakest) Acetate ion < Fluoride ion < Ammonia (strongest)

Question 80

After completing the following unfinished table, what is the order of increasing acid strength ?
Acid K _a p K _a Propanoic acid 1.3×10 ^{- 5} Chlorous acid 1.96 Benzoic acid 6.3×10 ^{- 5}

A) (weakest) Propanoic acid < Chlorous acid < Benzoic acid (strongest)
B) (weakest) Propanoic acid < Benzoic acid < Chlorous acid (strongest)
C) (weakest) Chlorous acid < Propanoic acid < Benzoic acid (strongest)
D) (weakest) Benzoic acid < Chlorous acid < Propanoic acid (strongest)
E) (weakest) Benzoic acid < Propanoic acid < Chlorous acid (strongest)