- A$n = 3, \,l = 2,\, m = -2,\, s = +1/2$
- ✓$n = 4, \,l = 0,\, m = 0,\, s = +1/2$
- C$n = 4, \,l = 1,\, m = +1,\, s = +1/2$
- D$n = 5, \,l = 0,\, m = 0,\, s = +1/2$
$(ii)$ For the same sum of $n+l$, the orbital with lower value of $n$ is filled first.
Lower be the sum, lower be the energy of electron.
$(iii)$ Electrons are filled in increasing order of energy. Thus, among the given options, $n +1$ for:
$(a)\,4+0=4$
$(b)\,4+1=5$
$(c)\,5+0=5$
$(d)\,3+2=5$
Hence $(a)$ i.e. $4+0=4$, is the correct answer.
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Statement $(I)$ : Fusion of $\mathrm{MnO}_2$ with $\mathrm{KOH}$ and an oxidising agent gives dark green $\mathrm{K}_2 \mathrm{MnO}_4$.
Statement $(II)$ : Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.
In the light of the above statements, choose the correct answer from the options given below.
(Molar mass of $Fe =56\, g\, mol ^{-1}$ )