A ferric oxide crystallizes in a hexagonal close-packed array of oxide ions with two out of every three octahedral holes occupied by ferric ions. The formula of the ferric oxide is-

1. FeO

2. Fe₂O₃

3. Fe₃O₄

4. Fe₃O₂

A compound forms a hexagonal close-packed structure. The total number of voids in 0.5 moles

of the compound will be -

$1.$ $9.033$ $\times$ ${10}^{23}$
$2.$ $3.011$ $\times$ ${10}^{23}$
$3.$ $6.023$ $\times$ ${10}^{23}$
$4.$ $8.024$ $\times$ ${10}^{23}$

A compound is formed by two elements M and N. The element N forms ccp and atoms of M occupy 1/3rd of tetrahedral voids. The formula of the compound would be -

1. MN

2. M₃N₄

3. M₂N₃

4. M₃N₂

In a cubic close-packed structure, the coordination number of atoms is -

1. 12

2. 8

3. 1

4. 4

A cubic solid is made of two elements P and Q. Atoms of Q occupy the corners of the cube and P occupy the body centre. The formula of this compound and the coordination number of Q are respectively - 

1. PQ, 8

2. P₂Q, 8

3. P₂Q₂, 8

4. PQ, 12

If the radius of the octahedral void is r and the radius of the atoms in close packing is R, the relation between r and R would be -

1. r = 0.114R

2. r = 0.444R

3. r = 1.414R

4. r = 0.414R