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]$3d^5$ where d-orbital is half filled and thus, very stable.

Q. Assertion : Two electrons of helium atom are placed in only one shell but three electrons of lithium need two shells.
Reason: A shell can have maximum ${\text{2n}}^2$ electrons.

Q. Assertion: The compressibility factor for $H_2$​ and $He$ is $(1+\frac{Pb}{RT})$
Reason: The compressibility factor for $H_2$​ and $He$ can be derived from Van der Waal's equation.

Q. Assertion : In the bonding molecular orbital (MO) of $H_2$, the electron density is increased between the nuclei.
Reason : The bonding MO is ${\psi }_A+{\psi }_B$, which shows destructive interference of the combining electron waves.

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