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Chemistry Assertion (A) & Reason (B) MCQ

Model Paper 2 · Rajasthan Board (RBSE) STD 11 Science (Rajasthan - English Medium). 4 questions.

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Assertion (A) & Reason (B) MCQ

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4 questions · timed · auto-graded

MCQ 11 Mark
Assertion (A): In the dissociation of $PCl _5$ at constantp ressure and temperature, addition of helium at equilibrium increases the dissociation of $PCl _5$.
Reason (R): Helium reacts with $Cl _2$ and hence shifts the equilibrium in forward direction.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: C.
A is true but R is false.
(c) A is true but R is false.
Explanation: Equilibrium shift in backword direction.
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MCQ 21 Mark
Assertion (A): In 285cm there are 3 significant figures.
Reason (R): Zero preceding to first non-zero digit are not significant.
  • A
    Both A and R are true and R is the correct explanation of A.
  • ✓
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: B.
Both A and R are true but R is not the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A .
Explanation: All non-zero digits are significant. For example, in 285 cm , there are three significant figures and in 0.25 mL , there are two significant figures.
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MCQ 31 Mark
Assertion (A): Components of a mixture of red and blue inks can be separated by distributing the components between stationary and mobile phases in paper chromatography.
Reason (R): The coloured components of inks migrate at different rates because paper selectively retains different components according to the difference in their partition between the two phases.
  • ✓
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: A.
Both A and R are true and R is the correct explanation of A.
(a)Both A and R are true and R is the correct explanation of A .
Explanation: In paper chromatography, a special quality paper known as chromatography paper is used. Chromatography paper contains water trapped in it, which acts as the stationary phase. A strip of chromatography paper spotted at the base with the solution of the mixture is suspended in a suitable solvent or a mixture of solvents. This solvent acts as the mobile phase. The solvent rises up the paper by capillary action and flows over the spot. The paper selectively retains different components according to their differing partition in the two phases. The paper strip so developed is known as a chromatogram. The spots of the separated coloured compounds are visible at different heights from the position of the initial spot on the chromatogram.
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MCQ 41 Mark
Assertion (A): Trans-2-butene on reaction with $Br _2$ gives a meso-2,3-dibromobutane.
Reason (R): The reaction involves the syn-addition of bromine.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • ✓
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Correct option: C.
A is true but R is false.
(c) A is true but R is false.
Explanation: With trans-2-butene, the product of Br2 addition is optically inactive due to the formation of symmetric meso compounds.
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Assertion (A) & Reason (B) MCQ - Chemistry STD 11 Science Questions - Vidyadip