Graphite and diamond are ________.

(a)

Covalent and molecular crystals

(b)

ionic and covalent crystals

(c)

both covalent crystals

(d)

both molecular crystals

An ionic compound A_x B_y crystallizes in fcc type crystal structure with B ions at the centre of each face and A ion occupying corners of the cube the correct formula of A_xB_y is ________.

(a)

AB

(b)

AB₃

(c)

A₃B

(d)

A₈B₆

The ratio of close packed atoms to tetrahedral hole in cubic packing is ________.

(a)

1:1

(b)

1:2

(c)

2:1

(d)

1:4

Solid CO₂ is an example of ________.

(a)

Covalent solid

(b)

metallic solid

(c)

molecular solid

(d)

ionic solid

Assertion: monoclinic sulphur is an example of monoclinic crystal system
Reason: for a monoclinic system, \(a\neq b\neq c\) and \(\alpha =\gamma ={ 90 }^{ 0 },\beta \neq { 90 }^{ 0 }\) 
Codes:
a) Both assertion and reason are true and reason is the correct explanation of assertion
b) Both assertion and reason are true but reason is not the correct explanation of assertion.
c) Assertion is true but reason is false.
d) Both assertion and reason are false.

(a)

Both assertion and reason are true and reason is the correct explanation of assertion

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false.

(d)

Both assertion and reason are false.