JEE Main 2023 — Chemistry Inorganic Chemistry

(i) The oxidation state of $\mathrm{Mn}$Mn in oxide (${\mathrm{Mn}}_{2}{O}_{7}$Mn2​O7​) is:

Let us consider $\mathrm{Mn}$Mn as $x$x.

$$\Rightarrow 2x+7(-2)=0$$⇒2x+7(−2)=0

$$\Rightarrow 2x+(-14)=0$$⇒2x+(−14)=0

$$\Rightarrow 2x-14=0$$⇒2x−14=0

$$\Rightarrow 2x=14$$⇒2x=14

$$\Rightarrow x=7$$⇒x=7

(ii) The oxidation state of Ruthenium in oxide (${\mathrm{RuO}}_{4}$RuO4​) is:

Consider $\mathrm{Ru}$Ru as $x$x.

$$\Rightarrow x+4(-2)=0$$⇒x+4(−2)=0

$$\Rightarrow x-8=0$$⇒x−8=0

$$\Rightarrow x=8$$⇒x=8

The oxidation state of Osmium in oxide (${\mathrm{OsO}}_{4}$OsO4​) is:

Consider $\mathrm{Os}$Os as $x$x.

$$\Rightarrow x+4(-2)=0$$⇒x+4(−2)=0

$$\Rightarrow x-8=0$$⇒x−8=0

$$\Rightarrow x=8$$⇒x=8

Hence, Ruthenium and Osmium has +7 oxidation state in its oxide.

(iii) $\mathrm{Sc}$Sc has ${\mathrm{ns}}^{2}(n-1){d}^{1}$ns2(n−1)d1 electronic configuration.

It utilizes two electrons from its $\mathrm{ns}$ns sub-shell then its oxidation state = +2. When it utilizes both the electrons then its oxidation state = +3.

(iv) In the modern periodic table, chromium metal is present in group 6. It is a transition metal and belongs to the first transition series. The atomic number of chromium is 24. Its electronic configuration is $[\mathrm{Ar}]3{d}^{5}4{s}^{1}$[Ar]3d54s1.

It has five electrons in the 3d sub-shell and one electron in the 4s sub-shell. Thus, chromium metal has six valence electrons. Chromium can lose some or all of its valence electrons to form ions with different oxidation states. Thus, chromium shows the oxidation states of +1, +2, +3, +4, +5, and +6 respectively.

The most common oxidation states of chromium are +2, +3, and +6.

So, the statement (i), (ii) and (iv) are correct.