#### 12th Standard Chemistry English Medium Solid State Reduced Syllabus Important Questions With Answer Key 2021

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 100

Multiple Choice Questions

15 x 1 = 15
1. Solid CO2 is an example of

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

2. In a solid atom M occupies ccp lattice and $\left( \cfrac { 1 }{ 3 } \right)$ 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

3. 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

4. Which of the following cannot be regarded as molecular solid?

(a)

Silicon carbide

(b)

AIN

(c)

Diamond

(d)

All the above

5. What is the relation between diamond and graphite?

(a)

Polymorphous

(b)

Isomer

(c)

Isotope

(d)

Isomorphous

6. A binary solid A+B- has a structure with B- ions constituting the lattice and A+ ions occupying 25% tetrahedral holes. Formula of the solid is

(a)

A2B

(b)

AB2

(c)

AB

(d)

AB4

7. The empty space between the shaded balls and hollow balls as shown in the diagram is called,

(a)

Hexagonal void

(b)

Octahedral void

(c)

Tetrahedral void

(d)

Double triangular void

8. An element with atomic mass 60 having fee structure has a density of 6.23g/cm3. what is the edge length of unit cell?

(a)

200 Pm

(b)

300 Pm

(c)

400 Pm

(d)

500 Pm

9. Pick out the example for covalent and molecular crystal.

(a)

Ice,Diamond

(b)

Diamond,Ice

(c)

NaCl, FeS

(d)

FeS,Ice

10. Which one of the following statements is wrong about Frenkel defect?

(a)

An ion occupies an interstitial position

(b)

Anion is much larger in size than the cation

(c)

The crystal remains neutral

(d)

Non-stoichiometric compound is formed

11. Which of the following exists as covalent crystals in solid state?

(a)

phosphorus

(b)

sulphur

(c)

chlorine

(d)

silicon

12. Which among the following is an amorphous solid?

(a)

Graphite

(b)

SiO2

(c)

Sic

(d)

Diamond

13. Examples of hydrogen bonded molecular solids

(a)

H2O

(b)

glucose

(c)

urea

(d)

all the above

14. An example of covalent crystalline solid is ________

(a)

NaI

(b)

AI

(c)

Si

(d)

Ar

15. If electrical conductivity is found to be I same in all directions through a solid the substance is __________ solid and the property is called _________

(a)

crystalline, isotropy

(b)

amorphous, isotropy

(c)

crystalline, anisotropy

(d)

amorphous, isotropy

1. 2 Marks

10 x 2 = 20
16. Define unit cell

17. Differentiate crystalline solids and amorphous solids.

18. Explain briefly seven types of unit cell

19. Distinguish between hexagonal close packing and cubic close packing.

20. Why do solids have a definite volume?

21. What type of stoichiometric defect is shown by ZnS.

22. Ionic solids conduct electricity in molten state but not in solid state. Explain.

23. Which point effect in crystal doesn't alter the density of the relevant solid?

24. Define void.

25. Diamond and solid rhombic sulphur are covalent solids but the latter has very low melting point than the former. Explain why?

1. 3 Marks

10 x 3 = 30
26. Write short note on metal excess and metal deficiency defect with an example

27. Why ionic crystals are hard and brittle?

28. What is the two dimensional coordination number of a molecule in square close packed layer?

29. Why are solids rigid?

30. If NaCI is doped with 10-3 mol % of SrCl2 What is the concentration of cation valencies?

31. Classify the following solids in different categories based on the nature of intermolecular force operating in them: Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide.

32. ZnO turns yellow on heating. Why?

33. How do the spacings of the three planes (100), (101) and (111) of simple cubic lattice vary?

34. Diffraction angle 2θ equal to 14.8o for a crystal having interplanar distance in the crystal is 0.400 nm when second order diffraction was observed. Calculate the wavelength of X-ray used.

35. State Bragg's law.

1. 5 Marks

7 x 5 = 35
36. An element has bcc structure with a cell edge of 288 pm. the density of the element is 7.2 gcm-3. how many atoms are present in 208g of the element.

37. KF crystallizes in fcc structure like sodium chloride. calculate the distance between K+ and F in KF.( given : density of KF is 2483. gcm-3)

38. Write a note on Frenkel defect.

39. Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

40. What are the general characteristics of solids?

41. How are crystals classified?

42. What are stoichiometric defects in ionic solids? Explain