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Statement 1 : In any ionic solid (MX) wi...

Statement 1 : In any ionic solid (MX) with Schottky defects, the number of positive and negative ions are same.

A

Both A and R are true and R is the correct explanation of A

B

Both A and R are true but R is not a correct explanation of A

C

A is true but R is false

D

A is false but R is true

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The correct Answer is:
A
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Statement I: In any ionic solid [MX] with Schottky defect, the number of positive and negative ions are same. Statement II: An equal number of cation and anion vacancies is present.

Statement I: In any ionic solid [MX] with Schottky defect, the number of positive and negative ions are same. Statement II: An equal number of cation and anion vacancies is present.

In the following question, a statement of assertion is followed by a statement of reason. Mark the correct choice. Assertion : In any ionic solid [MX] with schottky defects, the number of positive and negative ions are same. Reason : Equal number of cation and aniojn vacancies are present .

Ionic solids with Schottky defects contain in their structure

Any deviation from the perfectly ordered arrangement constitutes a defect or imperfection. The compounds in which the number of irregularity are present in the arrangement of atoms or ions are called atomic imperfections or point defects. These may be stochiometric or non - stoichlometric. Stoichiometric defects are further classified into Schottky defects in which number of positive and negative ions are missing in equal ratio and Frenkel defects in which an ion leaves its correct lattice sites and occupies on interstitial site. Schottky defect is more common in ionic compounds with high co-ordination number and where the size of positive and negative ions are almost equal, while in Frenkel defects are common in ionic compounds, which have low co-ordination number and in which there is large difference in size between positive and negative ions. In a crystal some ions are missing from normal sites. This is an example of

Any deviation from the perfectly ordered arrangement constitutes a defect or imperfection. The compounds in which the number of irregularity are present in the arrangement of atoms or ions are called atomic imperfections or point defects. These may be stochiometric or non - stoichlometric. Stoichiometric defects are further classified into Schottky defects in which number of positive and negative ions are missing in equal ratio and Frenkel defects in which an ion leaves its correct lattice sites and occupies on interstitial site. Schottky defect is more common in ionic compounds with high co-ordination number and where the size of positive and negative ions are almost equal, while in Frenkel defects are common in ionic compounds, which have low co-ordination number and in which there is large difference in size between positive and negative ions. Which of the following defect, if present, lowers the density of the crystal ?

Solids with Schottky defects are electrical insulators.

In an ideal crystal, the entropy of the constituents at absolute zero temperature (0K) is zero. However, the crystals generally suffer from certain defects also called imperfections They may be both electronic and atomic in nature. The atomic imperfections may be stoichiometric (Schottky and Frenkel defects) or non-stoichiometric (metal excees and metal deficiency defects). In addition to these, there are impurity defects which are caused by the addition of certain impurities of metals and this is known as dopping. The dopping leads to semi conductors which may be either n-type or p-type in nature. In stoichiometric defects, the ratio of positive and negative ions as indicated by chemical formula of the compound:

What is Schottky defect in a solid ?

Defects which do not disturb the stoichiometry are called stochiometric defect. At the time of crystal formation an ion may not occupy its expected position leaving a void or hole at that site. As a metter of fact one positive and one negative ion are missing from their respective positions leaving behind a pair of holes. This vacancy is a Schottky defect. Due to this defect density decreases. Defect arises in which certain atoms or ions have migrated to interstitial position some distance removed from the holes which they vacated. In this case there is no change in the density of the crystal. In stoichiometric defects, the ratio of positive and negative ions as indicated by chemical formula of the compound