10.26. Comment on each of the following observations:
(a) The mobilities of the alkali metal ions in aqueous solution are Li⁺ < Na⁺ + < Rb+ < Cs+
(b) Lithium is the only alkali metal to form a nitride directly.
(c) E^? for M²⁺ (aq) + 2e^– → M(s) (where M = Ca, Sr, or Ba) is nearly constant.

<p><strong> (a) </strong>Smaller the size of the ion, more highly it is hydrated and hence greater is the mass of the hydrated ion and thus the ionic mobility become lesser. The extent of hydration decreases in the order.<br>Li⁺&nbsp;&lt; Na⁺&nbsp;&lt;k^{+&nbsp;&lt; Rb+&nbsp;&lt; Cs+<br>Thus the mobility of Cs+&nbsp;will be the highest&lt;/k}</p><p><strong> (b)</strong> Due to its smaller size lithium can form nitride directly as an exceptional behaviour unlike other alkali metals.</p><p><strong> (c) </strong>It is because reduction potential depends upon sublimation energy, ionisation energy and hydration energy. Their resultant is almost constant for these ions.</p>

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