Deck 14: Aqueous Equilibria: Acids and Bases

Question 1

An Arrhenius base is best defined as a

A)proton donor.
B)hydroxide acceptor.
C)substance that dissociates in water to produce aqueous hydrogen ions.
D)substance that dissociates in water to produce aqueous hydroxide ions.

Answer 1

substance that dissociates in water to produce aqueous hydroxide ions.

Question 2

When dissolved in water,which of the following compounds is an Arrhenius base?

A)CH₃OH
B)HOCl
C)KOH
D)KCl

Answer 2

KOH

Question 3

Which Br∅nsted-Lowry acid has the strongest conjugate base?

A)HBr
B)HClO₄
C)HF
D)HI

Answer 3

HF

Question 4

A Br∅nsted-Lowry acid is best defined as a substance that can

A)accept a hydroxide ion.
B)donate a hydroxide ion.
C)accept a proton.
D)donate a proton.

Question 5

What is the conjugate base of the Br∅nsted-Lowry acid HPO₄^2-?

A)H₃PO₄
B)H₂PO₄^-
C)HPO₄^2-
D)PO₄^3-

Question 6

What is the strongest Br∅nsted-Lowry acid in the chemical reaction shown below?
2 HNO₃(aq)+ Ba(OH)₂(aq)→ Ba(NO₃)₂(aq)+ 2 H₂O(l)

A)HNO₃
B)Ba(OH)₂
C)Ba(NO₃)₂
D)H₂O

Question 7

Write a balanced equation for the dissociation of the Br∅nsted-Lowry acid HSO₄^- in water.

A)HSO₄^-(aq)+ H₂O(l)⇌ H₂SO₄(aq)+ OH^-(aq)
B)HSO₄^-(aq)+ H₂O(l)⇌ SO₄^2-(aq)+ H₃O⁺(aq)
C)HSO₄^-(aq)+ H₂O(l)⇌ SO₃^2-(aq)+ OH^-(aq)
D)HSO₄^-(aq)+ H₂O(l)⇌ SO₃(g)+ OH^-(aq)+ H₂O(l)

Question 8

When dissolved in water,which of the following compounds is an Arrhenius acid?

A)HCN
B)NaOH
C)NaF
D)CH₃CH₂OH

Question 9

In the following chemical equation indicate the reactant that is a Br∅nsted-Lowry acid.
HCN(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ CN^-(aq)

A)HCN
B)H₂O
C)H₃O⁺
D)CN^-

Question 10

An Arrhenius acid is best defined as a

A)hydroxide donor.
B)proton acceptor.
C)substance that dissociates in water to produce aqueous hydrogen ions.
D)substance that dissociates in water to produce aqueous hydroxide ions.

Question 11

What are the conjugate acid-base pairs in the following chemical reaction?
NH₃(aq)+ H₂O(l)⇌ NH₄⁺(aq)+ OH^-(aq)

A)NH₃,H₂O and NH₄⁺,OH^-
B)NH₃,NH₄⁺ and H₂O,OH^-
C)NH₃,OH^- and H₂O,NH₄⁺
D)NH₃ and NH₄⁺

Question 12

Which one of the following can behave either as a Br∅nsted-Lowry acid or a Br∅nsted-Lowry base in an aqueous solution reaction?

A)HSO₃^-
B)NH₃
C)HI
D)H₃PO₄

Question 13

What is the conjugate acid of the Br∅nsted-Lowry base HAsO₄^2-?

A)H₂AsO₄^-
B)AsO₄^3-
C)H₂O
D)H₃O⁺

Question 14

What are the Br∅nsted-Lowry bases in the following chemical reaction?
C₅H₅N(aq)+ H₂O(l)⇌ C₅H₅NH+(aq)+ OH-(aq)

A)C₅H₅N,H₂O
B)C₅H₅N,C₅H₅NH⁺
C)C₅H₅N,OH^-
D)C₅H₅N,H₂O,OH^-

Question 15

What are the Br∅nsted-Lowry acids in the following chemical reaction?
HBr(sol)+ CH₃COOH(sol)⇌ CH₃C(OH)₂⁺(sol)+ Br^-(sol)

A)HBr,CH₃COOH
B)HBr,CH₃C(OH)₂⁺
C)CH₃COOH,CH₃C(OH)₂⁺
D)CH₃COOH,Br^-

Question 16

Which of the following Br∅nsted-Lowry acids does not behave as a strong acid when it is dissolved in water?

A)HBr
B)HCl
C)HNO₂
D)HClO₄

Question 17

Identify the conjugate acid/base pairs present in an aqueous solution of hydrogen sulfate ion,
HSO₄^-.

A)HSO₄^-/SO₄^2- and H₃O⁺/H₂O
B)H₂SO₄/HSO₄^- and H₂O/OH^-
C)HSO₄^-/H₂O and H₃O⁺/SO₄^2-
D)HSO₄^-/H₂O and H₂SO₄/OH^-

Question 18

Which Br∅nsted-Lowry base has the strongest conjugate acid?

A)CH₃CO₂^-
B)CN^-
C)F^-
D)NO₃^-

Question 19

Indicate all the Br∅nsted-Lowry acids in the following chemical reaction.
HCl(aq)+ H₂O(aq)⇌ H₃O⁺(aq)+ Cl^-(aq)

A)HCl,H₂O
B)HCl,H₃O⁺
C)HCl,Cl^-
D)HCl,H₂O,H₃O⁺

Question 20

Which one of the following species acts as a Br∅nsted-Lowry acid in water?

A)NaH
B)NH₄⁺
C)CH₃NH₂
D)C₆H₆

Question 21

From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths (strongest to weakest).
HClO₄(aq)+ H₂O(l)→ H₃O⁺(aq)+ ClO₄^-(aq)
HNO₂(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ NO₂^-(aq)

A)HClO₄ > H₃O⁺ > HNO₂
B)HClO₄ > HNO₂ > H₃O⁺
C)H₃O⁺ > HClO₄ > HNO₂
D)H₃O⁺ > HNO₂ > HClO₄

Question 22

What is the geometric shape of the hydrated proton;that is,the hydronium ion H₃O⁺?

A)angular
B)pyramidal
C)trigonal planar
D)tetrahedral

Question 23

The following pictures represent aqueous solutions of binary acids of the type HA where the water molecules have been omitted for clarity.
Arrange the acids in order of increasing acid strength.

A)D < C < A < B
B)D < C < B < A
C)D < B < A < C
D)D < A < C < B

Question 24

Calculate the hydronium ion concentration in an aqueous solution that contains 2.50 × 10^-4 M in hydroxide ion.

A)4)00 × 10^-9 M
B)4)00 × 10^-10 M
C)4)00 × 10^-11 M
D)5)00 × 10^-11 M

Question 25

An acidic solution at 25°C has

A)[H₃O⁺] > [OH^-] > 1 × 10^-7 M.
B)[H₃O⁺] > 1 × 10^-7 M > [OH^-].
C)[H₃O⁺] = [OH^-] > 1 × 10^-7 M.
D)[H₃O⁺] < 1 × 10^-7 M > [OH^-].

Question 26

Calculate the hydroxide ion concentration in an aqueous solution that contains 3.50 × 10^-3 M in hydronium ion.

A)2)86 × 10^-4 M
B)2)86 × 10^-11 M
C)2)86 × 10^-12 M
D)3)50 × 10^-12 M

Question 27

Which is not a hydrate of a proton?

A)H₃O⁺
B)H₉O₄⁺
C)H₂₅O₁₁⁺
D)H₄₃O₂₁⁺

Question 28

A solution with a hydrogen ion concentration of 3.25 × 10^-2 M is ________ and has a hydroxide concentration of ________.

A)acidic,3.08 × 10^-12 M
B)acidic,3.08 × 10^-13 M
C)basic,3.08 × 10^-12 M
D)basic,3.08 × 10^-13 M

Question 29

The following pictures represent aqueous solutions of binary acids of the type HA where the water molecules have been omitted for clarity.
Determine the strongest acid of the set.

A)A
B)B
C)C
D)D

Question 30

At 50°C the value of K_w is 5.5 × 10^-14.A basic solution at 50°C has

A)[H₃O⁺] < [OH^-] < 2 × 10^-7 M.
B)[H₃O⁺] < 2 × 10^-7 M < [OH^-].
C)[H₃O⁺] = [OH^-] < 2 × 10^-7 M.
D)[H₃O⁺] > 2 × 10^-7 M < [OH^-].

Question 31

Normal rainfall has a concentration of OH^- that is 3.98 × 10^-9.The concentration of H₃O⁺ in normal rainfall is

A)greater than 3.98 × 10^-9,and the rain is acidic.
B)greater than 3.98 × 10^-9,and the rain is basic.
C)less than 3.98 × 10^-9,and the rain is acidic.
D)less than 3.98 × 10^-9,and the rain is basic.

Question 32

From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths (strongest to weakest).
2 NaH(s)+ H₂O(l)→ 2 NaOH + H₂(g)
NH₃(aq)+ H₂O(l)⇌ NH₄⁺(aq)+ OH^-(aq)

A)H^- > OH^- > NH₃
B)H^- > NH₃ > OH^-
C)OH^-> H^- > NH₃
D)OH^- > NH₃ > H^-

Question 33

From the following chemical reactions determine the relative Br∅nsted-Lowry base strengths (strongest to weakest).
HNO₃(aq)+ H₂O(l)→ H₃O⁺(aq)+ NO₃^-(aq)
HF(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ F^-(aq)

A)HNO₃ > H₃O⁺ > HF
B)NO₃^- > H₂O > F^-
C)F^- > H₂O > NO₃^-
D)F^- > NO₃^- > H₂O

Question 34

A solution with a hydroxide ion concentration of 4.15 × 10^-4 M is ________ and has a hydrogen ion concentration of ________.

A)acidic,2.41 × 10^-10 M
B)acidic,2.41 × 10^-11 M
C)basic,2.41 × 10^-10 M
D)basic,2.41 × 10^-11 M

Question 35

If the ionization constant of water,K_w,at 40°C is 2.92 × 10^-14,then what is the hydronium ion concentration for a neutral solution?

A)[H₃O⁺] < 1.00 × 10^-7 M
B)[H₃O⁺] > 1.71 × 10^-7 M
C)[H₃O⁺] = 1.71 × 10^-7 M
D)[H₃O⁺] < 1.71 × 10^-7 M

Question 36

Using the conjugate acid-base pairs listed below,complete the following equation with the pair that gives an equilibrium constant K_c > 1.
_____ + HSO₃^- ⇌ _____ + H₂SO₃

A)CH₃CO₂H/ CH₃CO₂^-
B)HCO₂H/ HCO₂^-
C)HNO₂/NO₂^-
D)HNO₃/NO₃^-

Question 37

Using the conjugate acid-base pairs listed below,complete the following equation with the pair that gives an equilibrium constant K_c > 1.
_____ + H₂CO₃ ⇌ _____ + HCO₃^-

A)HF/F^-
B)HCl/Cl^-
C)HOCl/OCl^-
D)HSO₄^2-/SO₄^2-

Question 38

From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths (strongest to weakest).
HClO₄(sol)+ CH₃COOH(l)→ CH₃C₂(OH)₂⁺(sol)+ ClO₄^-(aq)
H₂SO₄(sol)+ CH₃COOH(l)⇌ CH₃C(OH)₂⁺(sol)+ HSO₄^-(sol)

A)HClO₄ > H₂SO₄ > CH₃COOH
B)HClO₄ > H₂SO₄ > CH₃C(OH)₂⁺
C)HClO₄ > CH₃COOH > H₂SO₄
D)HClO₄ > CH₃C(OH)₂⁺ > H₂SO₄

Question 39

The equilibrium constant,K,for the reaction shown below has a value 1.8 × 10^-5.In this reaction which is the strongest acid and which is the strongest base?
CH₃CO₂H(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ CH₃CO₂^-(aq)

A)CH₃CO₂H and CH₃CO₂^-
B)CH₃CO₂H and H₂O
C)H₃O⁺ and H₂O
D)H₃O⁺ and CH₃CO₂^-

Question 40

From the following chemical reactions determine the relative Br∅nsted-Lowry acid strengths (strongest to weakest).
HCl(aq)+ H₂O(l)→ H₃O⁺(aq)+ Cl^-(aq)
HCN(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ CN^-(aq)

A)HCl > HCN > H₃O⁺
B)HCl > H₃O⁺ > HCN
C)H₃O⁺ > HCl > HCN
D)HCN > H₃O⁺ > HCl

Question 41

At 25°C,the pH of a vinegar solution is 2.60.What are the values of [H₃O⁺] and [OH^-] in the solution?

A)3)99 × 10^-12 M,2.51 × 10^-3 M
B)2)51 × 10^-3 M,3.98 × 10^-12 M
C)2)51 × 10^-3 M,11.40 M
D)2)60 M,11.40 M

Question 42

What is the hydroxide ion concentration and the pH for a hydrochloric acid solution that has a hydronium ion concentration of 1.50 × 10^-4 M?

A)6)67 × 10^-10 M,4.82
B)6)67 × 10^-10 M,9.18
C)6)67 × 10^-11 M,3.82
D)6)67 × 10^-11 M,10.18

Question 43

What is the hydronium ion concentration of an acid rain sample that has a pH of 3.15?

A)1)41 × 10^-11 M
B)7)08 × 10^-4 M
C)3)15 M
D)10.85 M

Question 44

An acidic solution at 25°C will have a hydronium ion concentration ________ and a pH value ________.

A)[H₃O⁺] > 1 × 10^-7 M,pH > 7.00
B)[H₃O⁺] > 1 × 10^-7 M,pH < 7.00
C)[H₃O⁺] < 1 × 10^-7 M,pH > 7.00
D)[H₃O⁺] < 1 × 10^-7 M,pH < 7.00

Question 45

What is the hydroxide ion concentration of a lye solution that has a pH of 11.20?

A)6)31 × 10^-12 M
B)1)58 × 10^-3 M
C)2)80 M
D)11.20 M

Question 46

What is the hydronium ion concentration and the pH for an aqueous solution of NH₃ that has a hydroxide ion concentration of 2.25 × 10^-3 M?

A)4)44 × 10^-11 M,3.65
B)4)44 × 10^-11 M,10.35
C)4)44 × 10^-12 M,2.65
D)4)44 × 10^-12 M,11.35

Question 47

What is the pH of a solution prepared by dissolving 0.15 gram of solid CaO (lime)in enough water to make 2.00 L of aqueous Ca(OH)₂ (limewater)?
CaO(s)+ H₂O(l)→ Ca²⁺(aq)+ 2 OH^-(aq)

A)2)57
B)2)87
C)11.13
D)11.43

Question 48

Human tears have a concentration of H₃O⁺ that is 3.16 × 10^-8.The concentration of OH^- in human tears is

A)greater than 3.16 × 10^-7 and tears are acidic.
B)greater than 3.16 ×10^-7 and tears are basic.
C)less than 3.16 × 10^-7 and tears are acidic.
D)less than 3.16 × 10^-7 and tears are basic.

Question 49

What is the pH of a 0.020 M Ba(OH)₂ solution?

A)1)40
B)1)70
C)12.30
D)12.60

Question 50

What is the pH of a 0.020 M HClO₄ solution?

A)0)020
B)0)040
C)1)70
D)12.30

Question 51

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

A)4)8 - 6.0
B)6)0 - 7.6
C)7)6 - 8.2
D)> 8.2

Question 52

Calculate the pH for an aqueous solution of pyridine that contains 2.15 × 10^-4 M hydroxide ion.

A)4)65 × 10^-11
B)2)15 × 10^-4
C)3)67
D)10.33

Question 53

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

A)3)2 - 4.4
B)4)8 - 6.0
C)6)0 - 7.6
D)8)2 - 10.0

Question 54

What is the pH of a solution prepared by diluting 25.00 mL of 0.10 M HCl with enough water to produce a total volume of 100.00 mL?

A)1)00
B)1)60
C)2)00
D)3)20

Question 55

What is the approximate pH of a solution X that gives the following responses with the indicators shown?

A)3)2 - 4.4
B)4)8 - 6.0
C)6)0 - 7.6
D)8)2 - 10.0

Question 56

If the ionization constant of water,K_w,at 40°C is 2.92 × 10^-14,then what is the hydronium ion concentration and pH for an acidic solution?

A)[H₃O⁺] > 1.71 × 10^-7 M and pH > 6.77
B)[H₃O⁺] > 1.71 × 10^-7 M and pH < 6.77
C)[H₃O⁺] < 1.71 × 10^-7 M and pH > 6.77
D)[H₃O⁺] < 1.71 × 10^-7 M and pH < 6.77

Question 57

Calculate the pH for an aqueous solution of acetic acid that contains 2.15 × 10^-3 M hydronium ion.

A)4)65 × 10^-12
B)2)15 × 10^-3
C)2)67
D)11.33

Question 58

What statement is most consistent for an acid with a pH = 3?

A)one one-hundredth as strong as an acid with a pH of 5
B)half a strong as an acid with a pH = 5
C)twice as strong as an acid with a pH of 5
D)one hundred times as strong as an acid with a pH = 5

Question 59

What is the pH of a 0.020 M RbOH solution?

A)0)020
B)0)040
C)1)70
D)12.30

Question 60

What is the pH of a solution prepared by diluting 25.00 mL of 0.020 M Ba(OH)₂ with enough water to produce a total volume of 250.00 mL?

A)2)40
B)2)70
C)11.30
D)11.60

Question 61

The pH of 0.150 M CH₃CO₂H,acetic acid,is 2.78.What is the value of K_a for acetic acid?

A)2)8 × 10^-6
B)1)9 × 10^-5
C)1)7 × 10^-3
D)1)1 × 10^-2

Question 62

Vinegar is a 5.0% solution by weight of acetic acid (CH₃CO₂H)in water.Given that the pH for acetic acid is 2.41,the K_a = 1.8 × 10^-5 and assuming the density of vinegar to be 1.00 g/cm³,what is the percent dissociation of acetic acid in vinegar?

A)0)47%
B)1)5%
C)4)0%
D)5)0%

Question 63

What is the equilibrium constant expression (K_a)for the acid dissociation of nitrous acid HNO₂? The equation of interest is
HNO₂(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ NO₂^-(aq).

A)K_a = ([H₃O⁺][NO₂^-])/([HNO₂][H₂O])
B)K_a = ([H₃O⁺][NO₂^-])/([HNO₂])
C)K_a = ([HNO₂][H₂O])/([H₃O⁺][NO₂^-])
D)K_a = ([HNO₂])/([H₃O⁺][NO₂^-])

Question 64

What is the pH of a solution made by mixing 100.0 mL of 0.10 M HNO₃,50.0 mL of 0.20 M HCl,and 100.0 mL of water? Assume that the volumes are additive.

A)0)30
B)0)82
C)1)00
D)1)10

Question 65

Determine the acid dissociation constant for a 0.10 M acetic acid solution that has a pH of 2.87.Acetic acid is a weak monoprotic acid and the equilibrium equation of interest is
CH₃COOH(aq)+ H₂O(l)⇌H₃O⁺(aq)+ CH₃CO2₃^-(aq)

A)1)3 × 10^-2
B)1)3 × 10^-3
C)1)8 × 10^-5
D)1)8 × 10^-6

Question 66

Potassium hydrogen phthalate (molar mass = 204.2 g/mol)is one of the most commonly used acids for standardizing solutions containing bases.KHP is a monoprotic weak acid with K_a = 3.91 × 10^-6.Calculate the pH of the solution that results when 0.40 g of KHP is dissolved in enough water to produce 25.0 mL of solution.

A)2)10
B)3)26
C)4)30
D)5)41

Question 67

Para-Aminobenzoic acid (PABA),p-H₂NC₆H₄(COOH),is used in some sunscreens and hair conditioning products.Calculate the pH of an aqueous solution with [PABA] = 0.030 M and
K_a = 2.2 × 10^-5.

A)1)52
B)3)09
C)4)66
D)6)18

Question 68

What is the hydronium ion concentration of a 0.100 M hypochlorous acid solution with
K_a = 3.5 × 10^-8? The equation for the dissociation of hypochlorous acid is:
HOCl(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ OCl^-(aq).

A)1)9 × 10^-4
B)5)9 × 10^-4
C)1)9 × 10^-5
D)5)9 × 10^-5

Question 69

What is the equilibrium constant expression (K_a)for the acid dissociation of hydrocyanic acid HCN? The equation of interest is
HCN(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ CN^-(aq).

A)K_a = ([H₃O⁺][CN^-])/([HCN][H₂O])
B)K_a = ([H₃O⁺][CN^-])/([HCN])
C)K_a = ([HCN][H₂O])/([H₃O⁺][CN^-])
D)K_a = ([HCN])/([H₃O⁺][CN^-])

Question 70

What is the pH of a solution made by mixing 100.00 mL of 0.20 M HCl with 50.00 mL of 0.10 M HCl? Assume that the volumes are additive.

A)0)15
B)0)52
C)0)78
D)1)70

Question 71

Determine the acid dissociation constant for a 0.020 M formic acid solution that has a pH of 2.74.Formic acid is a weak monoprotic acid and the equilibrium equation of interest is
HCOOH(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ HCO₂^-(aq).

A)1)8 × 10^-3
B)1)8 × 10^-4
C)3)6 × 10^-4
D)3)6 × 10^-5

Question 72

What is the hydronium ion concentration of a 0.100 M acetic acid solution with a K_a = 1.8 × 10^-5? The equation for the dissociation of acetic acid is:
CH₃CO₂H(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ CH₃CO₂^-(aq).

A)1)3 × 10^-2 M
B)4)2 × 10^-2 M
C)1)3 × 10^-3 M
D)4)2 × 10^-3 M

Question 73

Benzoic acid (C₆H₅CO₂H = HBz)solutions are sometimes used in experiments to determine the molarity of a basic solution of unknown concentration.What is the pH of a 0.100 M solution of benzoic acid if K_a = 6.5 × 10^-5 and the equilibrium equation of interest is
HBz(aq)+ H₂O(l)⇌ H₃O⁺ + Bz^-(aq)?

A)1)00
B)2)59
C)4)19
D)5)19

Question 74

The pH of 0.255 M HCN is 4.95.What is the value of K_a for hydrocyanic acid?

A)1)3 × 10^-10
B)4)9 × 10^-10
C)1)1 × 10^-5
D)4)4 × 10^-5

Question 75

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 M Ca(OH)₂ with 50.00 mL of 0.100 M NaOH? Assume that the volumes are additive.

A)12.67
B)12.78
C)12.95
D)13.25

Question 76

What is the percent dissociation of a benzoic acid solution with pH = 2.59? The acid dissociation constant for this monoprotic acid is 6.5 × 10^-5.

A)0)50%
B)1)5%
C)2)5%
D)3)5%

Question 77

Determine the acid dissociation constant for a 0.010 M nitrous acid solution that has a pH of 2.70.Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is
HNO₂(aq)+ H₂O(l)⇌ H₃O⁺(aq)+ NO₂^-(aq).

A)8)0 × 10^-3
B)2)0 × 10^-3
C)5)0 × 10^-4
D)4)0 × 10^-4

Question 78

Vinegar is a 5.0% solution by weight of acetic acid (CH₃CO₂H)in water.Given that
K_a = 1.8 × 10^-5 for acetic acid and assuming the density of vinegar to be 1.00 g/cm³,what is the pH of this vinegar solution?

A)2)00
B)2)41
C)2)87
D)4)74

Question 79

A tablet containing 500.0 mg of aspirin (acetylsalicylic acid or HC₉H₇O₄)was dissolved in enough water to make 100 mL of solution.Given that K_a = 3.0 × 10^-4 for aspirin,what is the pH of the solution?

A)1)57
B)2)54
C)3)52
D)5)08

Question 80

What is the strongest monoprotic acid of the following set if all the acids are at 0.100 M concentration?

A)hydrofluoric acid with K_a = 3.5 × 10^-4
B)benzoic acid with K_a = 6.5 × 10^-5
C)acetic acid with K_a = 1.8 × 10^-5
D)hypochlorous acid with K_a = 3.5 × 10^-8