Increasing order of reactivity of the following compounds for S_N1 substitution is:

HF has highest boiling point among hydrogen halides, because it has :

What would be the molality of 20% (mass/ mass) aqueous solution of KI?
(molar mass of KI = 166 g mol^–1)

The correct statements among I to III are :
(I) Valence bond theory cannot explain the color exhibited by transition metal complexes.
(II) Valence bond theory can predict quantitatively the magnetic properties of transtition metal complexes.
(III) Valence bond theory cannot distinguish ligands as weak and strong field ones.