SOLID-STATE-QUIZ-7

Solid State Quiz-7

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Q1. The first order reflection (n=1) from a crystal of the X-ray from a copper anode tube (λ=1.54 Å)

occurs at an angle of 45°. What is the distance between the set of plane causing the diffraction?

•  0.1089 nm
•  0.1089 m
•  0.905 Å
•  1.089nm

Solution
nλ=2d sinθ  

1×1.54 = 2d sin45° 

1×1.54 = 2d × 0.850 

2d=1.54/0.850

    =0.905 Å 

Q2.In a face centred cubic arrangement off A and B atoms whose A atoms are at the corner of the unit cell and B atoms at the face centres. One of the A atom is missing from one corner in unit cell. The simplest formula of compound is :

•  
•  
•  
•  

Solution
No. of atoms of A from corners of unit cell =7 ×1/8=7/8

No. of atoms of B from faces of unit cell = 6 ×1/2=3 

Thus, A :B : :7/8 :3 or 7 :24 

Thus, formula is 

Q3.  For which crystal anion-anion contact is valid?

•   NaF
•  NaI
•  CsBr
•  KCl

Solution
Due to smaller size of F.

Q4. A solid metal has ccp or fcc structure. The relation of side of cube (a)and radius of atom (r) will be

•  a=2r
•  a=2√2r
•  a=4r/√3
•  √(3r/2)

Solution
In case of ccp or fcc structure 4r=√2a 

 ⇒ a=4r/√2 

 ∴ a=2√2r

Q5. The number of atoms present in a simple cubic unit cell are :

•  4
•  3
•  2
•  1

Solution
 The number of atoms present in sc, fcc and bcc unit cell are 1, 4, 2 respectively.

Q6. The packing efficiency of the two dimensional square unit cell shown below is

•  39.27%
•  68.02%
•  74.05%
•  78.54%

Solution

Q7. All the substances becomes diamagnetic at :

•  4 K
•  10 K
•  20 K
•  25 K

Solution
Most of the metals have their transition temperature (i.e., the temperature at which a substance starts to behave as super conductor) in the range of 2-5 K. .

Q8.For a covalent solid, the units which occupy lattice points are :

•  Atoms
•  TIons
•  Molecules
•  Electrons

Solution
In covalent molecules atoms occupy the lattice points.

Q9.If ‘a’ stands for the edge length of the cubic systems : simple cubic, body-centred cubic and

face-centered, then the ratio of radii of the spheres in these systems will be respectively:

•  
  
•  
•  
•  

Solution

Q10. In NaCl crystal each  ion is surrounded by

•  4ions
•  6ions
•  1ion
• 2ions

Solution
In NaCl crystal, ions adopt cubic close packed arrangement and  ions occupy all the octahedral sites. Therefore, Na and Cl have 1 : 1 stoichiometry. In other words, each  ion is surrounded by six ions which are disposed towards the corners of a regular octahedron. Similarly, each  ion is surrounded by six  ions.