Question

Which of the following is not a base?
A.NaOH
B.KOH
C.$N{H_4}OH$
D.${C_2}{H_5}OH$

Answer 1

Hint: Generally, bases are defined as chemical substances that tend to donate electrons, release hydroxide ions or accept protons when dissolved in water. Moreover, bases are known to increase the hydroxide ion activity or reduce the hydronium ion activity when they are dissolved in aqueous media.

Complete step by step answer:
Base is defined as a substance that releases hydroxide ions when dissolved in aqueous media. They are bitter in taste and are slippery to touch. Moreover, they undergo chemical reactions with acidic substances to form salts. They hold the hydroxide ions that are either partially or completely displaceable.
Now, alkali are the bases that are soluble in water. Usually this term is used to denote the ionic salts of alkaline earth metals or alkali metals that exhibit basic qualities. Some common examples of alkali salts are magnesium hydroxide, sodium hydroxide, calcium hydroxide etc. moreover, under standard conditions, the pH value of a basic solution is always greater than 7. Further, the powerful bases are also known to have caustic effects on organic matter.
Now, among the given options KOH, NaOH and $N{H_4}OH$ are bases because they give $O{H^ - }$ ions in the solution. But ethanol i.e. ${C_2}{H_5}OH$ does not give $O{H^ - }$ ions because it weakly dissociates in water and hence it is not a base.
Hence, option D is correct.

Note:It can be noted that ammonia is sometimes excluded from the alkali family despite the fact that it facilitates the formation of hydroxide ions when dissolved in water. Moreover, we have three types of bases; monoacidic, diacidic and triacidic bases. In case of monoacidic base, one hydroxide ion is produced when one of its molecules undergo complete ionization whereas in diacidic base, two hydroxide ions are produced and in triacidic bases three hydroxide ions are produced.