Question

The pair of amphoteric hydroxides is:
A. \[Be{{\left( OH \right)}_{2}}\]and \[Zn{{\left( OH \right)}_{2}}\]
B. \[Al{{\left( OH \right)}_{3}}\]and LiOH
C. \[B{{\left( OH \right)}_{3}}\]and \[Be{{\left( OH \right)}_{2}}\]
D. \[Be{{\left( OH \right)}_{2}}\]and \[Mg{{\left( OH \right)}_{2}}\]

Answer 1

Hint: Amphoteric oxides are the oxides which can react with the acid and base both of them readily. Many elements exhibit this property in the periodic table such as Lead, Tin, Aluminum, Boron, etc.

Complete step by step answer:
The hydroxides are formed when the OH group is bonded to an element which is usually a metal. The hydroxides of alkali earth metals such as Lithium, Potassium, Sodium forms the most stable bases and strongest. All alkaline earth metals form hydroxides which are soluble but less stable than the alkali earth metals.
B. \[Al{{\left( OH \right)}_{3}}\]and LiOH, first the formula of oxide is wrong here and lithium hydroxide forms basic oxide as stated above.

C. \[B{{\left( OH \right)}_{3}}\]and \[Be{{\left( OH \right)}_{2}}\], in this option, the Boron forms acidic hydroxides, moreover they’re not much stable, hence, this option is wrong here.

D. \[Be{{\left( OH \right)}_{2}}\]and \[Mg{{\left( OH \right)}_{2}}\], in this option, Magnesium again forms basic hydroxides and hence, it is not amphoteric and that’s why this option is also not valid.

A. \[Be{{\left( OH \right)}_{2}}\]and \[Zn{{\left( OH \right)}_{2}}\], in this option, Beryllium forms oxides which react with acid and bases readily and zinc also.
So, the correct answer is “Option D”.

Note: Zinc Hydroxide is used in the surgical dressings as an absorbent to absorb the moisture and a very important intermediate in the formation of insecticide and pesticide. It occurs naturally in three rare minerals named as wulfenite, sweetite and ashoverite. In this question, Aluminum hydroxide is given which is used as an antacid agent as syrup.