Question

The number of replaceable \[\text{O}{{\text{H}}^{-}}\]ions in a base is called_________
A. Acidity of a base
B. Basicity of an acid
C. Neutral
D. Hydrolysis

Answer 1

Hint: An acid is defined as a substance which contains hydrogen and which when dissolved into water gives H+ ion. Whereas a base is defined as a substance which contains hydroxyl \[\left( \text{O}{{\text{H}}^{-}} \right)\]groups and which when dissolved in water gives hydroxides\[\left( \text{O}{{\text{H}}^{-}} \right)\] ion.

Complete step by step answer:
 Acidity: - The number of hydroxyl ions in a base is known as acidity of base. On the basis of no. of OH- ion these are further divided into three kinds i.e.:
Monoacidic bases: The base which having one OH- group e.g. KOH,\[\text{N}{{\text{H}}_{\text{4}}}\text{OH}\], NAOH etc.
Di-acidic bases: The base which having two OH- group e.g.\[\text{Ca}{{\left( \text{OH} \right)}_{\text{2}}}\],\[\text{Fe}{{\left( \text{OH} \right)}_{\text{2}}}\],\[\text{Zn}{{\left( \text{OH} \right)}_{\text{2}}}\].
Tri-acidic bases: The base which having three \[\left( \text{O}{{\text{H}}^{-}} \right)\]group e.g.\[\text{Fe}{{\left( \text{OH} \right)}_{\text{3}}}\], \[\text{Al}{{\left( \text{OH} \right)}_{\text{3}}}\]

So, the correct answer is “Option A”.

Additional Information:
Classical concept of acid and base
Acid was defined as a substance whose aqua solution possessed the following characteristic properties:
Conducts electricity,Reacts with active metals like zinc magnesium extractor to give hydrogen,Turns blue,litmus red,Has a sour taste,Who are acidic properties disappear on reaction with base.
Base was defined as a substance whose aqua solution for just the following characteristics properties:
Conduct electricity,Turns red litmus blue,Has a bitter taste,Has a soapy touch,Whose basic properties are destroyed on the reaction with an acid.
Arrhenius concept of acid and base
Acid: - An acid is defined as a substance which contains hydrogen and which was dissolved into water gives hydrogen ion.
Base: - a base is defined as a substance which contains hydroxyl group and when dissolved in water gives hydroxide ion.
Bronsted – Lowery concept of acids and bases
An acid is defined as a substance which has the tendency to give a proton and base is defined as a substance which has density except of proton. In other words, an acid is a proton donor where as a base is a proton acceptor.

Note:
The concept of acid, base, basicity, acidity must be clear to understand the statement. Basicity is no. of hydrogen ion present in an acid whereas acidity is no. of OH- ion present in an acid.
A strong acid has more concentration of hydrogen ions whereas a strong base has more concentration of hydroxyl ions. Hydrochloric acid is an example of strong acid and Sodium hydroxide is an example of strong base.