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Chemistry Assertion (A) & Reason (B) MCQ

Structure of Atom · Rajasthan Board (RBSE) STD 11 Science (Rajasthan - English Medium). 3 questions.

Questions

Assertion (A) & Reason (B) MCQ

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3 questions · self-marked practice — reveal the answer and mark yourself.

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): All isotopes of a given element show the same type of chemical behaviour.
Reason (R): The chemical properties of an atom are controlled by the number of electrons in the atom.
  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:

All isotopes of an element have same number of electrons and same electronic configuration; hence their chemical properties are also same. 

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Question 21 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): It is impossible to determine the exact position and exact momentum of an electron simultaneously.
Reason (R): The path of an electron in an atom is clearly defined.
  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true and R is not the correct explanation of A.
  3. A is true and R is false.
  4. Both A and R are false.
Answer
  1. A is true and R is false.

Explanation:

The effect of Heisenberg Uncertainty Principal is significant only for motion of microscopic objects and is negligible for that of macroscopic objects.

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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): Black body is an ideal body that emits and absorbs radiations of all frequencies.
Reason (R): The frequency of radiation emitted by a body goes from a lower frequency to higher frequency with an increase in temperature.
  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 explanation of A.
  3. A is true and R is false.
  4. Both A and R are false.
Answer
  1. Both A and R are true but R is not the explanation of A.

Explanation:

The ideal body, which emits and absorbs radiations of all frequencies, is called a black body and the radiation emitted by such a body is called black body radiation. The exact frequency distribution of the emitted eadiation (i.e. intensity versus frequency curve of the radiation) from a black body depends only on its temperature. At a given temperature, intensity of radiation emitted increases with decrease of wavelength, reaches a maximum value at a given wavelength and then starts decreasing with further decrease of wavelength.

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