If electrical conductivity is found to be 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

Coordination number of tetrahedral and octahedral voids respectively are________.

(a)

2,4

(b)

4,2

(c)

4,6

(d)

6,4

Crystals of NaCI has yellow colour due the presence of_________.

(a)

cation vaccancy

(b)

F centres

(c)

both (a) and (b)

(d)

neither (a) nor (b)

Structure of B₂O₃ is _____.

(a)

trigonal planar

(b)

tetrahedral

(c)

octahedral

(d)

cubic

The correct order of packing efficiency in different types of unit cells is________.

(a)

fcc > bcc > sc

(b)

sc < fcc < bcc

(c)

fcc < bcc > sc

(d)

bcc < fcc < sc