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Chemistry Assertion (A) & Reason (B) MCQ

Equilibrium · Rajasthan Board (RBSE) STD 11 Science (Rajasthan - English Medium). 9 questions.

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Assertion (A) & Reason (B) MCQ

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9 questions · timed · auto-graded

Question 11 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): The ionisation of hydrogen sulphide in water is low in the presence of hydrochloric acid.
Reason (R): Hydrogen sulphide is a weak acid.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. Both A and R are true but R is not correct explanation of A.

Explanation:

In presence of H+ ion, equilibrium shifts in backward direction.

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Question 21 Mark
Direction: In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. Both assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. Assertion is true but Reason is false.
  4. Both Assertion and Reason are false.
Assertion: A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of pH on addition of small amounts of acid or alkali.
Reason: A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around pH 4.75.
Answer
  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
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Question 31 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): A solution containing a mixture of acetic acid and sodium acetate maintains a constant value of pH on addition of small amounts of acid or alkali.
Reason (R): A solution containing a mixture of acetic acid and sodium acetate acts as a buffer solution around pH 4.75.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. Both A and R are true but R is not the correct explanation of A.

Explanation:

The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called buffer solutions.

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Question 41 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): An aqueous solution of ammonium acetate can act as a buffer.
Reason (R): Acetic acid is a weak acid and NH4OH is a weak base.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not correct explanation of A.
  3. A is false but R is true.
  4. Both A and R are false.
Answer
  1. A is false but R is true.

Explanation:

Salt of weak acid and weak base can form buffer solution.

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Question 51 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): In the dissociation of PCl5 at constant pressure and temperature addition of helium at equilibrium increases the dissociation of PCl5.
Reason (R): Helium removes Cl2 from the field of action.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. A is false but R is true.

Explanation:

If the volume is kept constant and an inert gas such as argon is added which does not take part in the reaction, the equilibrium remains undisturbed.

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Question 61 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question
Assertion (A): Increasing order of acidity of hydrogen halides is.
HF < HCl < HBr < HI
Reason (R): While comparing acids formed by the elements belonging to the same group of periodic table, H - A bond strength is a more important factor in determining acidity of an acid than the polar nature of the bond.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not the correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. Both A and R are true and R is the correct explanation of A.

Explanation:

$\frac{\text{H}-\text{F}<\text{H}-\text{Cl}<\text{H}-\text{Br}<\text{H}-\text{I}}{\text{Increasing acidic character}}$

Weaker is the covalent bond, stronger is the acidic character.

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Question 71 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): Aqueous solution of ammonium carbonate is basic.
Reason (R): Acidic/ basic nature of a salt solution of a salt of weak acid and weak base depends on Ka and Kb value of the acid and the base forming it.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. Both A and R are true and R is correct explanation of A.

Explanation:

Ka and Kb values are responsible for acidic and basic characters of substances.

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Question 81 Mark
Note: In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct option out of the choices given\ below each question.
Assertion (A): For any chemical reaction at a particular temperature, the equilibrium constant is fixed and is a characteristic property.
Reason (R): Equilibrium constant is independent of temperature.
  1. Both A and R are true and R is correct explanation of A.
  2. Both A and R are true but R is not correct explanation of A.
  3. A is true but R is false.
  4. Both A and R are false.
Answer
  1. A is true but R is false.

Explanation:

  • The equilibrium constant for an exothermic reaction $($negative $\Delta\text{H})$ decreases as the temperature increases.
  • The equilibrium constant for an endothermic reaction $($positive $\Delta\text{H})$ increases as the temperature increases.
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Question 91 Mark
Direction: In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. Both assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. Assertion is true but Reason is false.
  4. Both Assertion and Reason are false.
Assertion: Increasing order of acidity of hydrogen halides is HF < HCl < HBr < HI
Reason: While comparing acids formed by the elements belonging to the same group of periodic table, H-A bond strength is a more important factor in determining acidity of an acid than the polar nature of the bond.
Answer
  1. Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
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