Assertion :The third ionization energy of manganese (At no. 25) unexpectedly high. Reason: Loss of two electrons gives the configuration of $M n^{2 +}$ as; [Ar] $3 d^{5}$ where d-orbital is half filled and thus, very stable.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Both Assertion and Reason are incorrect

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Atomic no. of Mn = 25 and electronic configuration is: $[A r] 4 s^{2} 3 d^{5}$ . Loss of two electrons gives the configuration of $M n^{2 +}$ as [Ar] $3 d^{5}$ where d-orbital is half filled and thus very stable. Therefore the third ionisation energy is very high as the third electron is to be removed from the stable configuration of $M n^{2 +}$ .

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Q. Read the assertion and reason carefully to mark the correct option out of the options given below:

(a)If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b)If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c)If assertion is true but reason is false.

(d)If assertion is false but reason is true.
Assertion : EV(M

^{2 +}

/M) value for copper is positive (+0.34V).
Reason : High ionization enthalpy and low heat of hydration energy

Assertion (A) Boiling points of alcohols and ethers are high.
Reason (R) They can form intermolecular hydrogen-bonding.
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(e) Both assertion and reason are correct statements but reason is not correct explanation of assertion.

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Assertion :The third ionization energy of manganese (At no. 25) unexpectedly high. Reason: Loss of two electrons gives the configuration of Mn2+ as; [Ar]3d5 where d-orbital is half filled and thus, very stable.

Assertion :The third ionization energy of manganese (At no. 25) unexpectedly high. Reason: Loss of two electrons gives the configuration of $M n^{2 +}$ as; [Ar] $3 d^{5}$ where d-orbital is half filled and thus, very stable.