Match the defects in column 1 with statements given in column 2 and mark the appropriate choice.
(A) Simple vacancy defect
(i)Shown by non-ionic solids and increases the density of the solid
(B) Simple interstitial defect
(ii)Shown by ionic solution and decreases the density of the solid
(C) Frenkel defect
(iii)Shown by non-ionic solids and decreases the density of the solid
(iv)Shown by ionic solids and density of the solid remains the same
A. (A)$\to $(iv), (B)$\to $(iii), (C)$\to $(ii), (D)$\to $(i) B. (A)$\to $(iii), (B)$\to $(iv), (C)$\to $(i), (D)$\to $(ii) C. (A)$\to $(iii), (B)$\to $(i), (C)$\to $(iv), (D)$\to $(ii) D. (A)$\to $(i), (B)$\to $(iii), (C)$\to $(iv), (D)$\to $(ii)
Hint: We should know about different types of defects that occur in solid due to deviation in the arrangement of constituting particles. We should know that in a crystalline solid, when the ideal arrangement of solids is distorted around a point or atom it is called a point defect.
Complete answer: We will take each defect from the option and then we will know about each. - So, first in column 1 is a simple vacancy defect. Simple vacancy defect is a type of point defect in a crystal where an atom is missing from one of the lattice sites. We should know that vacancies are formed during solidification due to vibration of atoms, local rearrangement of atoms, plastic deformation and ionic bombardments. So, by removing the atom the density decreases in the type of solid. So, A in column 1 should be matched with (iii) in column 2. - In option B, it is an interstitial defect. Interstitial defect happens when an atom in the lattice takes the interstitial position of the lattice structure. This interstitial atom can be from the same crystal or from a foreign material. It increases the density of the liquid. So, from this we can say that it matches with (i) in column 2. - Now, we will know about Frenkel defects. Frenkel defect is another form of a point defect which is created when an atom or cation leaves its original place in the lattice structure to create a vacancy while occupying another interstitial position within the solid crystal. So, the density of the solid remains the same here. Therefore, it should be matched with option (iv) in column 2. - Now, Let’s see the Schottky defect. Schottky defect is a type of point defect or imperfection in solids which is caused by a vacant position that is generated in a crystal lattice due to the atoms or ions moving out from the interior to the surface of the crystal. It should be matched with (ii) in column 2.
So, we can say that option C is the correct answer.
Note:Do not get confused between Frenkel and Schottky defect. Frenkel defects are mostly exhibited in ionic solids where the smaller ion (usually the cation) is dislocated. Some of the examples include AgBr, ZnS, AgCl, and AgI. Examples of Schottky defect are Sodium Chloride (NaCl), Potassium Chloride (KCl), Potassium Bromide (KBr), Caesium Chloride (CsCl) and Silver Bromide (AgBr).
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