Ionic Equilibrium · Chemistry · COMEDK

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MCQ (Single Correct Answer)

1
The ionisation constant of the weak acid HF whose concentration is 0.1 M is $3.5 \times 10^{-4}$ The Equilibrium constant value for the reaction $\mathrm{F}^{-}+\mathrm{H}_2 \mathrm{O} \leftrightharpoons \mathrm{HF}+\mathrm{OH}^{-}$is _________ and the pH of aqueous solution of the weak acid is __________ .
COMEDK 2025 Afternoon Shift
2
Imagine an R - moiety of a pentapeptide molecule having one $-\mathrm{SH},-\mathrm{CONH}_2,-\mathrm{NH}_2$ groups each and two $-$COOH groups in the amino acids forming the pentapeptide. If the pH is maintained at 13.2, what would be the total number of negative charges on the pentapeptide?
COMEDK 2025 Afternoon Shift
3
What volume of $0.2 \mathrm{M} \mathrm{CH}_3 \mathrm{COOH}$ needs to be added to 100 ml of $0.4 \mathrm{M} \mathrm{CH}_3 \mathrm{COONa}$ solution to prepare a buffer of pH equal to 4.91 ? ( $\mathrm{pK}_{\mathrm{a}}$ of $\mathrm{CH}_3 \mathrm{COOH}$ is 4.76 )
COMEDK 2025 Morning Shift
4
Solubility product of the sparingly soluble salt $\mathrm{AgBrO}_3$ in aqueous medium is $9.3 \times 10^{-10}$ Calculate the mass in gram of $\mathrm{AgBrO}_3$ present in 100 ml of its saturated solution. (Molar mass of $\mathrm{AgBrO}_3$ is $236 \mathrm{~g} / \mathrm{mol}$ )
COMEDK 2025 Morning Shift
5
The conductivity of 0.01 M solution of $\mathrm{CH}_3 \mathrm{COOH}$ at 298 K is $1.65 \times 10^{-4} \mathrm{Scm}^{-1}$ What is the $\mathrm{pK}_{\mathrm{a}}$ value of the acid if $\lambda^0\left(\mathrm{H}^{+}\right)$and $\lambda^0\left(\mathrm{CH}_3 \mathrm{COO}\right)^{-1}$ are $349.1 \mathrm{Scm}^2 \mathrm{~mol}^{-1}$ and $40.9 \mathrm{Scm}^2 \mathrm{~mol}^{-1}$ respectively?
COMEDK 2025 Morning Shift
6

What volume of $$0.2 \mathrm{~M}$$ Acetic acid is to be added to $$100 \mathrm{ml}$$ of $$0.4 \mathrm{M}$$ Sodium acetate so that a Buffer solution of $$\mathrm{pH}$$ equal to 4.94 is obtained? $$(\mathrm{pK}_{\mathrm{a}}$$ of $$\mathrm{CH}_3 \mathrm{COOH}=4.76)$$

COMEDK 2024 Evening Shift
7

$$ 1 \mathrm{~cm}^3 \text { of } 0.01 \mathrm{~M} \mathrm{~HCl} \text { is added to } 1 \mathrm{~L} \text { of } \mathrm{NaCl} \text { solution. The } \mathrm{pH} \text { of the resulting solution is: } $$

COMEDK 2024 Afternoon Shift
8

$$\mathrm{A}_3 \mathrm{~B}_4$$ is a sparingly soluble salt with a solubility of $$\mathrm{s} g / \mathrm{L}$$. If the Molar mass of $$\mathrm{A}_3 \mathrm{~B}_4$$ is $$\mathrm{Mg} / \mathrm{mol}$$, what is the expression for its $$\mathrm{K}_{\text {sp }}$$ ?

COMEDK 2024 Morning Shift
9

$$300 \mathrm{ml}$$ of an aqueous solution of $$\mathrm{NaOH}$$ with $$\mathrm{pH}$$ value of 10 is mixed with $$200 \mathrm{ml}$$ of an aqueous solution of $$\mathrm{HCl}$$ with a $$\mathrm{pH}$$ value of 4. What will be the $$\mathrm{pH}$$ of the resultant solution at room temperature?

COMEDK 2024 Morning Shift
10

In a $$0.2 \mathrm{~M}$$ aqueous solution, lactic acid is $$6.9 \%$$ dissociated. The value of dissociation constant is

COMEDK 2023 Morning Shift
11

A buffer solution has equal volumes of $$0.1 \mathrm{~M} \mathrm{~NH}_4 \mathrm{OH}$$ and $$0.01 \mathrm{~M} \mathrm{~NH}_4 \mathrm{Cl}$$. The $$\mathrm{pK}_b$$ of the base is 5. The $$\mathrm{pH}$$ is

COMEDK 2023 Morning Shift
12

What would be the volume of water required to dissolve $$0.2 \mathrm{~g}$$ of $$\mathrm{PbCl}_2$$ of molar mass $$278 \mathrm{~g} / \mathrm{mol}$$ to prepare a saturated solution of the salt? $$(\mathrm{K}_{\mathrm{SP}}$$ of $$\mathrm{PbCl}_2=3.2 \times 10^{-8})$$

COMEDK 2023 Evening Shift
13

pH of 10$$^{-3}$$ M solution of KOH is

COMEDK 2022
14

Hydroxyl ion concentration of 1M HCl is

COMEDK 2020
15

Which of the following salts on being dissolved in water gives pH > 7 at 25$$^\circ$$C ?

COMEDK 2020
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