SATHEE: The sBlock Elements - Result Question 7

The sBlock Elements - Result Question 7

####7. The sequence of ionic mobility in aqueous solution is :

[2008]

(a) $K^{+} > N a^{+} > R b^{+} > C s^{+}$

(b) $C s^{+} > R b^{+} > K^{+} > N a^{+}$

(d) $N a^{+} > K^{+} > R b^{+} > C s^{+}$

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Solution:

(b) Smaller the ion more is its ionic mobility in aqueous solution. Ionic radii of the given alkali metals is in the order $N a^{+} < K^{+} < R b^{+} < C s^{+}$ and thus expected ionic mobility will be in the same order $C s^{+} < R b^{+} < K^{+} < N a^{+}$ . However due to high degree of solvation (or hydration) and because of lower size or high charge density, the hydrated ion size follows the same order $C s^{+} < R b^{+} < K^{+} < N a^{+}$ and thus conductivity order is $C s^{+} > R b^{+} > K^{+} > N a^{+}$ .

(d) The stability of alkali metal hydrides decreases from $L i$ to Cs. It is due to the fact that $M - H$ bonds becomes weaker with increase in size of alkali metals as we move down the group from $L i$ to Cs. Thus the order of stability of hydrides is

$L i H > N a H > K H > R b H > C s H$

The sBlock Elements - Result Question 7

Solution:

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The sBlock Elements - Result Question 7

Solution:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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