AFor the ionic compound MgO a Schottky defect would consist

A.For the ionic compound MgO, a Schottky defect would consist of:

1.One Mg vacancy and one O vacancy.

2.One Mg vacancy and one Mg interstitial

3.One O vacancy and one Mg interstitial

4.Two Mg vacancies and three Mg interstitials

5.None of the above

B.For the ionic compound MgO, a Frenkel defect would consist of:

Solution

Answer- A

Schottky defect-  

In ionic crystals, the defect forms when oppositely charged ions leave their lattice sites, creating vacancies.

Since both ions(cation,anoion) leave lattice and create vacancies in schottky defect - options 2,3,4 can not be answer as one of the ion is forming interstitals in these options.

Option 1 satisfies all conditions of schottky defect.

Therefore Answer--- 1) One Mg vacancy and one O vacancy

Answer B -

Frenkel defect-

Frenkel defect is the defect in the molecule where an atom or ion (normally the cation) leaves its own lattice site vacant and instead occupies a interstitial site.

option 4 can not be the answer as frenkel defect is a neutral defect butif Two Mg vacancies and three Mg interstitials are formed neutrality will be lost.

option 1 can not be the answer as frenkel defects include interstial.

option 3 can not be the answer as the same ion leaves its position and occupies interstitial site in frenkel defect but in given option O creates vacancy whil Mg occupies interstitial site.

Therefore answer 2- as it satisfies all condition of frenkel defect- a) neutrality is maintained

b) same ion creates vacancy and occupies interstitial site

Answer-- 2 ) One Mg vacancy and one Mg interstitial