Question

Which of the following is the strongest base?
A.LiOH
B.KOH
C.CsOH
D.NaOH

Answer 1

Hint:We should know that here in chemistry the base is the one which can either accept the hydrogen ions or it can donate the pair of valence electrons.
Also according to the fajans rule greater the size of the atom from the hydroxyl group stronger is the base.

Complete step-by-step answer:We should know that here in chemistry the base is the one which can either accept the hydrogen ions or it can donate the pair of valence electrons.
we should know that the basic character depends upon the ease with which they donate the electrons. From this we come to know that more the ease of donating stronger is the base.
Considering the above question we consider the fajans rule according to that rule as the hydroxide ion is the smaller one and lithium is also too small which makes it more covalent hence,it can produce the hydroxyl ions much due to which it becomes the weak base. Then ,considering the potassium hydroxide we come to the fact that as the size of potassium is bigger and also it forms the ionic bond more comfortably therefore it is more basic in nature. Now throwing the light on the third option we come to know that as the size of Cs is very larger than according to the fajans rule it is the stronger base. Then coming to the last option we come to know that sodium hydroxide is also a strong base but the size is less than potassium hydroxide which is in turn slightly smaller than Cs .

So option C is the correct option for the above question and CsOH is the strongest base amongst the others.

Note:We should use one rule throughout inorder to determine the strongest acid or the base as the different criteria will not give the proper comparison between them.