How many of the following orders are correct :
(i) `LiOH gt NaOH gt KOH` (Solubility in water)
(ii) `LiHCO_(3) lt NaHCO_(3) lt KHCO_(3)` (Solubility in water)
(iii) `Li_(2)CO_(3) lt Na_(2)CO_(3) lt K_(2)CO_(3)` (Solubility in water)
(iv ) `LiCl gt NaCl gt KCl gt RbCl`(Lattice energy)

Options

A. 1 and 4
B. 1 and 3
C. 1 and 2
D. 2 and 3

Answer

A

Explanation

Basic strength of the oxides increase in the order `Li_(2)O lt Na_(2)O lt K_(2)O lt Rb_(2)O lt Cs_(2)O`. The increase in basic strength is due to the decrease in I.E. and increase in electropositive character.
The melting points of hte halides decrease in the order `NaF gt NaCl gt NaBr gt NaI`, as the size of the halide ion increases. The decrease in melting the size of anion according to Fajan.s rule.