Question

The weakest base among NaOH, Ca(OH)2 ,KOH, Be(OH)2?

Answer 1

it is Be(OH)2

Explanation:

basically all ionics with a Hydroxide (`OH^-`) that are in group one or two in the periodic table (alkali metals and alkaline earth) are strong bases except Be and Mg. All the rest of the bases are considered weak also.

Since Na, Ca, and K are all in group one or two, they are strong bases. Be(OH)2 is one of the exceptions to this rule so it's a weak base :)