Crystals NAT Level – 1 - Physics MCQ

Crystal size = 1 cm
Size of unit cell = 1 nm

For fee structure, number of atoms per unit cell = 4
Number of atoms = 4x10²¹
The correct answer is: 4

Sodium has one conduction electron and bcc structure, for bcc structure, number of atoms in unit cell = 2.
Number of conduction electrons = 2x1 =2.
Concentration 
The correct answer is: 3.125

The correct answer is: 8890

Na has bcc structure.
Nearest neighbour distance 


The correct answer is: 0.212

The correct answer is: 6.3

For [1 1 1] Plane, d=a/√(1²+1²+1²)=a/√3

                             2dsinθ=λ

For smallest angle, θ=sin^-1(λ/2d)

θ=sin^-1(λ/2d)

  =sin^-1(λ/(2a/√3)=sin^-1(√3x0.71/2x6.3)

=> θ=5.6^o

So the correct answer is 5.6.

⇒ 2θ = 180°
⇒ θ = 82°
The correct answer is: 82

r - 0.28 nm
⇒ 2r = 0.56 nm
= 5.6 
The correct answer is: 5.6

Area of the plane=a√h²+k²+l²

=>2√(1²+1²+1²)=3.464

The current answer: 3.464