CBSE Class 12 Chemistry The Solid State Worksheet

Question. A compound is formed by elements A and B. The crystalline cubic structure has the A atoms at the corners of the cube and B atoms at the body centre. The simplest formula of the compound is
(a) AB
(b) A6B
(c) AB₆
(d) A₈B4
Answer : A

Question. The number of atoms in 100 g of an fcc crystal with density, d = 10 g/cm³ and cell edge equal to 100 pm, is equal to
(a) 1 × 10²⁵
(b) 2 × 10²⁵
(c) 3 × 10²⁵
(d) 4 × 10²⁵
Answer : D

Question. How many unit cells are present in a cubeshaped ideal crystal of NaCl of mass 1.00 g ?
[Atomic masses : Na = 23, Cl = 35.5]
(a) 5.14 × 10²¹ unit cells
(b) 1.28 × 10²¹ unit cells
(c) 1.71 × 10²¹ unit cells
(d) 2.57 × 10²¹ unit cells
Answer : D

Question. If calcium crystallizes in bcc arrangement and the radius of Ca atom is 96 pm, then the volume of unit cell of Ca is
(a) 10.9 × 10^–36 m³
(b) 10.9 × 10^–30 m³
(c) 21.8 × 10^–30 m³
(d) 21.8 × 10^–36 m³
Answer : B

Question. The number of unit cells in the Ca atom lies on the surface of a cubic crystal that is 1.0 cm in length is
(a) 9.17 × 10²³
(b) 9.17 × 10²²
(c) 2 × 9.17 × 10²³
(d) 2 × 9.17 × 10²²
Answer : B

Question. The radii of Na⁺ and Cl^– ions are 95 pm and 181 pm respectively. The edge length of NaCl unit cell is
(a) 276 pm
(b) 138 pm
(c) 552 pm
(d) 415 pm
Answer : A

Question. An alloy of copper, silver and gold is found to have cubic lattice in which Cu atoms constitute ccp. If Ag atoms are located at the edge centres and Au atom is present at body centre, the alloy will have the formula
(a) CuAgAu
(b) Cu₄Ag₄Au
(c) Cu₄Ag₃Au
(d) Cu₄Ag₆Au
Answer : C

Question. The cubic unit cell of a metal (molar mass = 63.55g mol^–1) has an edge length of 362 pm. Its density is 8.92g cm^–3.
The type of unit cell is
(a) primitive
(b) face centered
(c) body centered
(d) end centered
Answer : B

Question. The pure crystalline substance on being heated gradually first forms a turbid liquid at constant temperature and still at higher temperature turbidity completely disappears. This behaviour is a characteristic property of substance forming.
(a) Allotropic
(b) Liquid
(c) Isomeric
(d) Isomorphous
Answer : B

Question. Which of crystal systems contains the maximum number of Bravais lattices?
(a) Cubic
(b) Hexagonal
(c) Triclinic
(d) Orthorhombic
Answer : D

Question. The second order Bragg diffraction of X-rays with = 1.00 Å from a set of parallel planes in a metal occurs at an angle 60º. The distance between the scattering planes in the crystal is
(a) 0.575 Å
(b) 1.00 Å
(c) 2.00 Å
(d) 1.15 Å
Answer : B

Question. In A⁺B^– ionic compound, radii of A⁺ and B^– ions are 180 pm and 187 pm respectively. The crystal structure of this compound will be
(a) NaCl type
(b) CsCl type
(c) ZnS type
(d) similar to diamond
Answer : B

Question. Which set of following characteristics for ZnS crystal is correct?
(a) Coordination number (4 : 4); ccp; Zn²⁺ ion in the alternate tetrahedral voids
(b) Coordination number (6 : 6); hcp; Zn²⁺ ion in all tetrahedral voids.
(c) Coordination number (6 : 4); hcp; Zn²⁺ ion in all octahedral voids
(d) Coordination number (4 : 4); ccp; Zn²⁺ ion in all tetrahedral voids.
Answer : A

Question. Total volume of atoms present in a face-centred cubic unit cell of a metal is (r is atomic radius)
(a) (12/3)πr³
(b) (16/3)πr³
(c) (20/3)πr³
(d) (24/3)πr³
Answer : B

Question. A solid is made of two elements X and Z. The atoms Z are in ccp arrangement while the atoms X occupy all the tetrahedral sites. What is the formula of the compound?
(a) XZ
(b) XZ2
(c) X2Z
(d) X2Z3
Answer : C

Question. The pyknometric density of sodium chloride crystal is 2.165 × 10³ kg m^–3 while its X-ray density is 2.178 × 10³ kg m^–3. The fraction of unoccupied sites in sodium chloride crystal is
(a) 5.96 × 10^–3
(b) 5.96 × 10⁴
(c) 5.96 × 10^–2
(d) 5.96 × 10^–1
Answer : A

Question. The edge length of unit cell of a metal having molecular weight 75 g/mol is 5Å which crystallizes in cubic lattice. If the density is 2g/cc then find the radius of metal atom.
(NA = 6 × 10²³). Give the answer in pm.
(a) 217 pm
(b) 210 pm
(c) 220 pm
(d) 205 pm
Answer : A

Question. In a normal spinel type structure , the oxide ions are arranged in ccp whereas 1/8 tetrahedral holes are occupied by Zn²⁺ ions and 50% of octahedral holes are occupied by Fe³⁺ ions .The formula of the compound is
(a) Zn₂Fe₂O₄
(b) ZnFe₂O₃
(c) ZnFe₂O₄
(d) ZnFe₂O₂
Answer : C

Question. To get a n- type semiconductor, the impurity to be added to silicon should have which of the following number of valence electrons
(a) 1
(b) 2
(c) 3
(d) 5
Answer : D

Question. Non stoichiometric defects are formed by
(a) s- block elements
(b) p-block elements
(c) either s-block elements or d-block elements
(d) only d-block elements.
Answer : D

Question. If NaCl is doped with 10^–4 mol % of SrCl₂, the concentration of cation vacancies will be (NA = 6.02 × 10²³ mol^–1)
(a) 6.02 × 10¹⁶ mol^–1
(b) 6.02 × 10¹⁷ mol^–1
(c) 6.02 × 10¹⁴ mol^–1
(d) 6.02 × 10¹⁵ mol^–1
Answer : B

Question. A molecule A₂B (Mwt. = 166.4) occupies triclinic lattice with a 5 Å, b = 8 Å, and c = 4 Å.
If the density of AB₂ is 5.2 g cm^–3, the number of molecules present in one unit cell is
(a) 2
(b) 3
(c) 4
(d) 5
Answer : B

Question. A mineral having the formula AB2 crystallizes in ccp lattice with A atoms occupying the lattice points. Pick out the correct statements of the following
(a) 100% occupancy of tetrahedral voids, C.N. of B = 4
(b) 100% occupancy of octahedral voids, C.N. of B = 4
(c) 50% occupancy of tetrahedral voids, C.N. of A = 4
(d) 100% occupancy of octahedral voids, C.N. of A = 4
Answer : A

Question. Schottky defect in crystals is observed when
(a) an ion leaves its normal site and occupies an interstitial site 
(b) unequal number of cations and anions are missing from the lattice
(c) density of the crystal increases
(d) equal number of cations and anions are missing from the lattice
Answer : D

Question. In a solid lattice the cation has left a lattice site and is located at an interstitial position, the lattice defect is
(a) Interstitial defect
(b) Vacancy defect
(c) Frenkel defect
(d) Schottky defect
Answer : C

Numeric Value Answer

Question. Pottasium has a bcc structure with nearest neighbour distance 4.52 Å. Its atomic weight is 39. Its density (in kg m_–3) will be
Answer : 910

Question. KCl crystallises in the same type of lattice as does NaCl. Given that r _Na+ / r_Cl¯ = 0.55 and r_K+/r_Cl¯ = 0.74. Calculate the ratio of the edge length of the unit cell for KCl to that of NaCl.
Answer : 1.123

Question. A metal has a fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is 2.72 g cm^-3. The molar mass of the metal is :
(NA Avogadro’s constant = 6.02 × 10²³ mol^–1)
Answer : 27

Question. The edge length of unit cell of a metal having molecular weight 75 g/mol is 5Å which crystallizes in cubic lattice. If the density is 2 g/cc and the radius of metal atom is 4.33 xpm. (N_A = 6 × 10²³). Find the value of x.
Answer : 5

Question. In face centred cubic (fcc) crystal lattice, edge length is 400 pm. The diameter of greatest sphere is 29.29 d pm which can be fit into the interstitial void without distortion of lattice. Find the value of d.?
Answer : 4

QUESTIONS

1. What are Bravais lattices?

2. Why are amorphous solids isotropic in nature?

3. Why glass is regarded as an amorphous solid?

4. Define the term 'crystal lattice.‟

5. Name the crystal system for which all four types of unit cells are possible. [Ans. Orthorhombic]

6. What is the total number of atoms per unit cell in a fcc crystal structure? [Ans. 4]

7. What difference in behaviour between the glass and sodium chloride would you expect to observe, if you break off a piece of either cube?

8. Define the term voids.

9. What type of stochiometric defect is shown by (i) ZnS and (ii) CsCl?

[Hint. : (i) Frenkel defect (ii) Schottky defect]

*10. If the formula of a compound is A2B, which sites would be occupied by A ions?

[Hint. : Number of A atoms is double to B, so it occupied tetrahedral void]

11. What is the coordination number for (a) an octahedral void (b) a tetrahedral void. [Hint. : (a) 6; (b) 4 ]

*12. How many octahedral voids are there in 1 mole of a compound having cubic closed packed structure?

13. What does the term „Coordination number‟ indicate

14. Arrange simple cubic, bcc and fcc lattice in decreasing order of the fraction of the occupied space.

15. How much space is empty in a hexagonal closed packed solid?

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