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Chemistry Assertion (A) & Reason (B) MCQ

Classification of Elements and Periodicity in Properties · Gujarat Board (GSEB) STD 11 Science (GSEB - English Medium). 3 questions.

Questions

Assertion (A) & Reason (B) MCQ

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3 questions · auto-graded multiple-choice test.

MCQ 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 $(A)$ : Generally, ionisation enthalpy increases from left to right in a period.
Reason $(R)$ : When successive electrons are added to the orbitals in the same principal quantum level, the shielding effect of inner core of electrons does not increase very much to compensate for the increased attraction of the electron to the nucleus.
  • A
    Assertion is correct statement and reason is wrong statement.
  • ✓
    Assertion and reason both are correct statements and reason is correct explanation of assertion.
  • C
    Assertion and reason both are wrong statements.
  • D
    Assertion is wrong statement and reason is correct statement.
Answer
Correct option: B.
Assertion and reason both are correct statements and reason is correct explanation of assertion.
Ionisation enthalpy increases from left to right across the period due to decrease in atomic size. The electron present within the subshell has almost same effective nuclear charge.
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MCQ 21 Mark
Assertion $(A)$ : Electron gain enthalpy becomes less negative as we go down a group.
Reason $(R)$ : Size of the atom increases on going down the group and the added electron would be farther from the nucleus.
  • A
    Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  • ✓
    Assertion and reason both are correct statements and reason is correct explanation for assertion.
  • C
    Assertion and reason both are wrong statements.
  • D
    Assertion is wrong statement but reason is correct statement.
Answer
Correct option: B.
Assertion and reason both are correct statements and reason is correct explanation for assertion.
On moving down the group, the electron gain enthalpy becomes less negative because on moving down the group the atomic size increases and the added electron lies away from the nucleus.
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MCQ 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 $(A)$ : Boron has a smaller first ionisation enthalpy than beryllium.
Reason $(R)$ : The penetration of a $2s$ electron to the nucleus is more than the $2p$ electron hence $2p$ electron is more shielded by the inner core of electrons than the $2s$ electrons.
  • A
    Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  • B
    Assertion is correct statement but reason is wrong statement.
  • ✓
    Assertion and reason both are correct statements and reason is correct explanation for assertion.
  • D
    Assertion and reason both are wrong statements.
Answer
Correct option: C.
Assertion and reason both are correct statements and reason is correct explanation for assertion.
Boron $\left(1 s^2 2 s^2 2 p^1\right)$ has less first ionisation enthalpy than beryllium $\left(1 s^2 2 s^2\right)$ because beryllium has fully filled. $s-$ sub shell. $2 s -$ electrons are nearer to the nucleus as compared to $2 s -$ electrons.
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