<p>(a) Account for the following:</p>

<p>(i) Manganese shows maximum nuber of oxidation states in 3d series.</p>

<p>(ii)&nbsp;<span class="equation">\(E^0\)</span>&nbsp;value for&nbsp;<span class="equation">\(Mn^{3+}/Mn^{2+}\)</span>couple is much more positive than that for <span class="equation">\(Cr^{3+}/Cr^{2+}\)</span>​​​​​​​</p>

<p>(iii)&nbsp;<span class="equation">\(Ti^{4+}\)</span>&nbsp;is colourless whereas <span class="equation">\(V^{4+}\)</span>&nbsp;is coloured in an aqueous solution.​​​​​​​​​​​​​​</p>

<p>(b) Write the chemical equations for the preparation of&nbsp;<span class="equation">\(KMnO_4\)</span>&nbsp;from <span class="equation">\(MnO_2\)</span>. Why does purple colour of acidified permanganate solution decolourise when it oxidises&nbsp;<span class="equation">\(Fe^{2+}\)</span>&nbsp;to&nbsp;<span class="equation">\(Fe^{3+}\)</span>​​​​​​​?&nbsp;​​​​​​​</p>