In hexagonal close packing of sphere in three dimensions.

(1) In one unit cell there are 12 octahedral voids and all are completely inside the unit cell.

(2) In one unit cell there are six octahedral voids and all are completely inside the unit cell.

(3) In one unit cell there are six octahedral void and of which three are completely inside the unit cell and other three are partially inside the unit cell.

(4) In one unit cell there are 12 tetrahedral voids, all are completely inside the unit cell.

Diamond has face-centred cubic lattice. There are two atoms at (0,0,0) and $\left(\frac{{\displaystyle 1}}{{\displaystyle 4}},\frac{{\displaystyle 1}}{{\displaystyle 4}},\frac{{\displaystyle 1}}{{\displaystyle 4}}\right)$coordinates.The ratio of the carbon-carbon bond distance to the edge of the unit cell is

(1) $\sqrt{\frac{3}{16}}$

(2) 4

(3) $\frac{1}{4}$

(4) $\frac{1}{\sqrt{2}}$

Spinel is an important class of oxides consisting of two types of metal ions with the oxide ions arranged inCCP pattern. The normal spinel has 1/ 8 of the tetrahedral holes occupied by one type of metal ion and 1/2 of the octahedral holes occupied by another type of metal ion. Such a spinel is formed by Zn²+, A1³* and 0^2-with Zn²+ in the tetrahedral holes. If CCP arrangement of oxide ions remains undistorted in the presence of all the cations, formula of spinel and fraction of the packing fraction of crystal are respectively :

(1) ZnAl₂O₄ , 77%

(2) ZnAl₂O₄, 74%

(3) Zn₂AlO₄, 74%

(4) Zn₃Al₂O_6,74%

What is the maximum number of layers of atoms in close-packed planes that will lie within two imaginary parallel planes having a distance between them of 13$\sqrt{\frac{2}{3}}$ R (where R is the radius of an atom) in the copper crystal (FCC)?
Consider the atoms to be within the parallel planes if their centers are on or within the two parallel planes.

1. 5

2. 6

3. 7

4. 8

Analysis show that nickel oxide consist of nickel ion with 96% ions having d⁸ configuration and 4% having d⁷ configuration. Which amongst the following best represents the formula of the oxide.

(1) Ni_1.02O_1.00

(2) Ni_0.96O_1.00

(3) Ni_0.96O_0.98

(4) Ni_0.98O_1.00

PCl₅ molecule has

(1) three fold axis of symmetry

(2) two fold axis of symmetry

(3) both

(4) none of these

Which of the following statements is correct about the conduction of electricity in pure crystal of silicon atroom temperature?

(1) The conduction is due to electrons present in fully occupied lowest energy states.

(2) The conduction is due to only some electrons capable of leaving the bonds at room temperature.

(3) The conduction is only due to the holes formed from the release of electrons.

(4) The conduction is due to the movement of both the electrons released and holes formed.

Calculate the Miller indices of crystal planes which cut through the crystal axes at (i) (2a, 3b, c), (ii) (∞, 2b, c )

(1) 3, 2, 6 and 0, 1, 2

(2) 4, 2, 6 and 0, 2, 1

(3) 6, 2, 3 and 0, 0, 1

(4) 7, 2, 3 and 1, 1, 1

Caculate the distance between 111 planes in a crystal of Ca. Repeat the calculation for the 222 planes. (a = 0.556nm)

(1) 016.1 nm

(2) 0.161 nm

(3) 0.610 nm

(4) None of the above

A metallic element crystallizes into a lattice containing a sequence of layers of ABABAB ............ Any packing of spheres leaves out voids in the lattice. The percentage by volume of empty space of this is

(1) 26%

(2) 21%

(3) 18%

(4) 16 %