Q. How many set of statements are correct?
(i) Solubility of alkali metal hydroxides is in order
$C s O H > R b O H > K O H > N a O H > L i O H$
(ii) Solubility of alkali carbonates is in order
$L i_{2} C O_{3} > N a_{2} C O_{3} > K_{2} C O_{3} > R b_{2} C O_{3} > C s_{2} O_{3}$ .
(iii) Hydrated radii is in order
$L i^{+} < N a^{+} < K^{+} < R b^{+} < C s^{+}$
(iv) Stability of peroxides is in order
$N a_{2} O_{2} < K_{2} O_{2} < R b_{2} O_{2} < C s_{2} O_{2}$

207 186 The s-Block Elements Report Error

Answer: 2

Solution:

(i), (iv)