| (I) Basic strength of oxides \[C{{s}_{2}}O<R{{b}_{2}}O<{{K}_{2}}O<N{{a}_{2}}O<L{{i}_{2}}O\] |
| (ii) (H) Stability of peroxides \[N{{a}_{2}}{{O}_{2}}<{{K}_{2}}{{O}_{2}}<R{{b}_{2}}{{O}_{2}}<C{{s}_{2}}{{O}_{2}}\] |
| (iii) Stability of bicarbonates \[LiHC{{O}_{3}}<NaHC{{O}_{3}}<KHC{{O}_{3}}<RbHC{{O}_{3}}<CsHC{{O}_{3}}\] |
| (iv) Melting point \[NaF<NaCl<NaBr<NaI\] |
A) I and IV
B) I and III
C) I and II
D) II and III
Correct Answer: A
Solution :
Basic strength of the oxides increase in the order \[{{\operatorname{Li}}_{2}}O<N{{a}_{2}}O<{{K}_{2}}O<R{{b}_{2}}O<C{{s}_{2}}O.\] The increase in basic strength is due to the decrease in I.E. and increase in electropositive character. The melting points of the halides decrease in the order\[\operatorname{NaF} > Nad > NaBr > Nal\], as the size of the halide ion increases. The decrease in melting point is due to increase in the covalent character with increase in the size of anion according to Fajan?s rule.
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