41. The Bragg’s diffraction equation is given by :

(a) sin θ= nλ/ 2d

(b) sin θ= n/2dλ

(c) sin θ= 2dnλ

(d) sin θ= 2(n–λd)

42. The donor impurity must have only ……. valence electrons.

(a) 2

(b) 3

(c) 4

(d) 5

43. The Miller indices of the diagonal plane of a cube are :

(a) 0 1 0

(b) 1 1 0

(c) 0 0 1

(d) 1 1 1

44. One angstrom is equal to :

(a) 10^–9 metre

(b) 10^–11 metre

(c) 10^–10 metre

(d) 10^–12 metre

45. Which one of the following materials does not have a covalent bond ?

(a) Silver

(b) Silicon

(c) Organic polymer

(d) Diamond

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