12th Chemistry - Book Back Answers - Unit 6 Solid State - English Medium Guides ~ Kalvi Tips

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Tamil Nadu Board 12th Standard Chemistry - Unit 6: Book Back Answers and Solutions

This post covers the book back answers and solutions for Unit 6 from the Tamil Nadu State Board 12th Standard Chemistry textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

By going through this material, you’ll gain a strong understanding of Unit 6 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following
2 Mark Questions: Answer briefly
3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 12 students! Prepare well and aim for top scores. Thank you!

I. Multiple Choice Questions

1. Graphite and diamond are

a) Covalent and molecular crystals

b) ionic and covalent crystals

c) both covalent crystals

d) both molecular crystals

Answer Key:

c) both covalent crystals

2. An ionic compound A_xB_y crystallizes in fcc type crystal structure with B ions at the centre of each face and A ion occupying corners of the cube. the correct formula of A_xB_y is

a) AB

b) AB₃

c) A₃B

d) A₈B₆

Answer Key:

b) AB₃

3. The ratio of close packed atoms to tetrahedral hole in cubic packing is

a) 1:1

b) 1:2

c) 2:1

d) 1:4

Answer Key:

b) 1:2

4. Solid CO₂ is an example of

a) Covalent solid

b) metallic solid

c) molecular solid

d) ionic solid

Answer Key:

c) molecular solid

5. Assertion : monoclinic sulphur is an example of monoclinic crystal system

Reason: for a monoclinic system, a≠b≠c and $α = γ = 90 °, β \neq 90 °$

a) Both assertion and reason are true and reason is the correct explanation of assertion.

b) Both assertion and reason are true but reason is not the correct explanation of assertion.

c) Assertion is true but reason is false.

d) Both assertion and reason are false.

Answer Key:

a) Both assertion and reason are true and reason is the correct explanation of assertion.

6. In calcium fluoride, having the flurite structure the coordination number of Ca²⁺ion and F- Ion are

a) 4 and 2

b) 6 and 6

c) 8 and 4

d) 4 and 8

Answer Key:

c) 8 and 4

7. The number of unit cells in 8 gm of an element X (atomic mass 40) which crystallizes in bcc pattern is (N_A is the Avogadro number)

a) 6.023 X 10²³

b) 6.023 X 10²²

c) 60.23 X 10²³

(\begin{matrix} \frac{6.023 X 1023}{8 \times 40} \end{matrix})

Answer Key:

b) 6.023 X 10²²

8. In a solid atom M occupies ccp lattice and $(\begin{matrix} \frac{1}{3} \end{matrix})$ of tetrahedral voids are occupied by atom N. find the formula of solid formed by M and N.

a) MN

b) M₃N

c) MN₃

d) M₃N₂

Answer Key:

d) M₃N₂

9. The ionic radii of A⁺ and B⁻ are 0.98 × 10⁻¹⁰m and 1.81 × 10^-10m . the coordination number of each ion in AB is

a) 8

b) 2

c) 6

d) 4

Answer Key:

c) 6

10. CsCl has bcc arrangement, its unit cell edge length is 400pm, its inter atomic distance is

a) 400pm

b) 800pm

\sqrt{3} \times 100 p m

(\begin{matrix} \frac{\sqrt{3}}{2} \end{matrix})

x 400pm

Answer Key:

(\begin{matrix} \frac{\sqrt{3}}{2} \end{matrix})

x 400pm

11. A solid compound XY has NaCl structure. if the radius of the cation is 100pm, the radius of the anion will be

(\begin{matrix} (\frac{100}{0.414}) \end{matrix})

()

(\begin{matrix} (\frac{0.732}{100}) \end{matrix})

c) 100 x 0.414

()

(\begin{matrix} (\frac{0.414}{100}) \end{matrix})

Answer Key:

(\begin{matrix} (\frac{100}{0.414}) \end{matrix})

12. The vacant space in bcc lattice unit cell is

a) 48%

b) 23%

c) 32%

d) 26%

Answer Key:

c) 32%

13. The radius of an atom is 300pm, if it crystallizes in a face centered cubic lattice, the length of the edge of the unit cell is

a) 488.5pm

b) 848.5pm

c) 884.5pm

d) 484.5pm

Answer Key:

b) 848.5pm

14. The fraction of total volume occupied by the atoms in a simple cubic is

(\begin{matrix} \frac{π}{4 \sqrt{2}} \end{matrix})

(\begin{matrix} \frac{π}{6} \end{matrix})

(\begin{matrix} \frac{π}{4} \end{matrix})

(\begin{matrix} \frac{π}{3 \sqrt{2}} \end{matrix})

Answer Key:

(\begin{matrix} \frac{π}{6} \end{matrix})

15. The yellow colour in NaCl crystal is due to

a) excitation of electrons in F centers

b) reflection of light from Cl- ion on the surface

c) refraction of light from Na+ ion

d) all of the above

Answer Key:

a) excitation of electrons in F centers

16. If ‘a’ stands for the edge length of the cubic system; sc , bcc, and fcc. Then the ratio of radii of spheres in these systems will be respectively.

(\begin{matrix} \frac{1}{2} a : \frac{\sqrt{3}}{2} a : \frac{\sqrt{2}}{2} a \end{matrix})

(\begin{matrix} \sqrt{1} a : \sqrt{3} a : \sqrt{2} a : \end{matrix})

(\begin{matrix} \frac{1}{2} a : \frac{\sqrt{3}}{2} a : \frac{1}{2 \sqrt{2}} a \end{matrix})

(\begin{matrix} \frac{1}{2} a : \sqrt{3} a : \frac{1}{\sqrt{2}} a \end{matrix})

Answer Key:

(\begin{matrix} \frac{1}{2} a : \frac{\sqrt{3}}{2} a : \frac{1}{2 \sqrt{2}} a \end{matrix})

17. If ‘a’ is the length of the side of the cube, the distance between the body centered atom and one corner atom in the cube will be

(\begin{matrix} \frac{2}{\sqrt{3}} \end{matrix})

(\begin{matrix} \frac{4}{\sqrt{3}} \end{matrix})

(\begin{matrix} \frac{\sqrt{3}}{4} \end{matrix})

(\begin{matrix} \sqrt{\frac{\sqrt{3}}{2}} \end{matrix})

Answer Key:

(\begin{matrix} \sqrt{\frac{\sqrt{3}}{2}} \end{matrix})

18. Potassium has a bcc structure with nearest neighbor distance 4.52 A⁰. its atomic weight is 39. its density will be

a) 915 kg m^-3

b) 2142 kg m^-3

c) 452 kg m^-3

d) 390 kg m^-3

Answer Key:

a) 915 kg m^-3

19. Schottky defect in a crystal is observed when

a) unequal number of anions and cations are missing from the lattice

b) equal number of cations and anions are missing from the lattice

c) an ion leaves its normal site and occupies an interstitial site

d) no ion is missing from its lattice.

Answer Key:

b) equal number of cations and anions are missing from the lattice

20. The cation leaves its normal position in the crystal and moves to some interstitial position, the defect in the crystal is known as

a) Schottky defect

b) F center

c) Frenkel defect

d) non-stoichiometric defect

Answer Key:

c) Frenkel defect

21. Assertion: due to Frenkel defect, density of the crystalline solid decreases.

Reason: in Frenkel defect cation and anion leaves the crystal.

a) Both assertion and reason are true and reason is the correct explanation of assertion.

b) Both assertion and reason are true but reason is not the correct explanation of assertion.

c) Assertion is true but reason is false.

d) Both assertion and reason are false

Answer Key:

d) Both assertion and reason are false

22. The crystal with a metal deficiency defect is

a) NaCl

b) FeO

c) ZnO

d) KCl

Answer Key:

b) FeO

23. A two dimensional solid pattern formed by two different atoms X and Y is shown below. The black and white squares represent atoms X and Y respectively. the simplest formula for the compound based on the unit cell from the pattern is

a) XY₈

b) X₄Y₉

c) XY₂

d) XY₄

Answer Key:

a) XY₈

II. Short Answer Questions.

12th Chemistry

III. Long Answer Questions.

12th Chemistry

IV. Exercise.

12th Chemistry