In the given TLC, the distance of spot A & B are 5 cm & 7 cm, from the bottom of TLC plate, respectively.

$$\mathrm{R}_{\mathrm{f}}$$ value of $$\mathrm{B}$$ is $$x \times 10^{-1}$$ times more than $$\mathrm{A}$$. The value of $$x$$ is __________.

Number of compounds from the following which cannot undergo Friedel-Crafts reactions is: _________

toluene, nitrobenzene, xylene, cumene, aniline, chlorobenzene, $$m$$-nitroaniline, $$m$$-dinitrobenzene

Total number of electrons present in $$\left(\pi^*\right)$$ molecular orbitals of $$\mathrm{O}_2, \mathrm{O}_2^{+}$$ and $$\mathrm{O}_2^{-}$$ is ________.

A transition metal '$$\mathrm{M}$$' among $$\mathrm{Sc}, \mathrm{Ti}, \mathrm{V}, \mathrm{Cr}, \mathrm{Mn}$$ and $$\mathrm{Fe}$$ has the highest second ionisation enthalpy. The spin-only magnetic moment value of $$\mathrm{M}^{+}$$ ion is _______ BM (Near integer)

(Given atomic number $$\mathrm{Sc}: 21, \mathrm{Ti}: 22, \mathrm{~V}: 23, \mathrm{Cr}: 24, \mathrm{Mn}: 25, \mathrm{Fe}: 26$$)