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Lithium borohydride (LiBH₄), crystallizes in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are:- a = 6.81 Å , b = 4.43 Å, c = 7.17 Å. If the molar mass of LiBH₄ is 21.76 g mol^-1, then the density of the crystal is:-
1. 0.67 g cm^-3
2. 0.58 g cm^-3
3. 1.23 g cm^-3
4. None of the above.

Which arrangement of electrons leads to anti-ferromagnetism?
1.

2.

3. Both (1) and (2)
4. None of the above.

The density of KCl is 1.9893 g cm^-3 and the length of a side unit cell is 6.29082 Å as determined by X-ray diffraction. The value of Avogadro’s number calculated from this data is:-
1. 6.017 x 10²³
2. 6.023 x 10²²
3. 7.03 x 10²³
4. 6.01 x 10¹⁹

8 : 8 co-ordination of CsCl is found to change into 6 : 6 co-ordination on:
1. Applying pressure.
2. Increasing temperature.
3. Both 1 and 2.
4. None of these.

Frenkel defect is not found in the halides of alkali metals because alkali metals have
1. High electropositivity.
2. High ionic radii.
3. High reactivity.
4. Ability to occupy interstitial sites.

Schottky defect occurs mainly in electrovalent compounds where :
1. Positive ions have large sizes.
2. Negative ions have small sizes.
3. Positive and negative ions are of similar size.
4. Positive ions are big and negative ions are small.

In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face
centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is
1.AB₂
2.A₂B₃
3.A₂B₅
4.A₂B

In a metal oxide, the oxide ions are arranged in hexagonal close packing and metal ions occupy two third of the octahedral voids. The formula of the oxide is : 
1. MO
2. M₂O₃
3. MO₂
4. M₂O

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

Silver metal crystallises in a cubic closest – packed arrangement with the edge of the unit cell having a length a = 407 pm. What is the radius of silver atom.
(1) 143.9 pm
(2) 15.6 pm
(3) 11.59 pm
(4) 13.61 pm

A metallic element exists as a cubic lattice. Each edge of the unit cell is 2.88 Å. The density of the metal is 7.20 g cm^–3.  The number of unit cells, that will be present in 100 gm of the metal is: 
1. 5.82 × 10²³
2. 16.33 × 10²³
3. 7.49 × 10²⁴
4. 6.9 × 10²⁴

The fraction of total volume occupied  by the atoms present in a simple cube is:
$$\begin{gathered} 1. \mathrm{\pi }/6 \\ 2. \mathrm{\pi }/3\sqrt{2} \\ 3. \mathrm{\pi }/4\sqrt{2} \\ 4. \mathrm{\pi }/4 \end{gathered}$$

Iron has a body centred cubic unit cell with the cell dimension of 286.65 pm. Density of iron is 7.87 g cm^-3. The value of  Avogadro's number based on this data will be -
(Atomic mass of Fe = 56.0 u)
1. 6.04 x 10²³ mol^-1
2. 12.08 x 10²⁴ mol^-1
3. 6 x 10²² mol^-1
4. 6 x 10^-23 mol^-1

Niobium crystallizes in body-centred cubic structure. If its density is 8.55 g cm^-3, calculate atomic radius of niobium, given its atomic mass 93u.
1.  149 cm
2.  143 $\mathrm{\rho m}$
3.  133 $\mathrm{\rho m}$
4.  143 cm

The unit cell dimensions of a cubic lattice (edges a, b, c and the angles between them, α, β, γ) are : 
1. a = b = c, $\mathrm{\alpha }= \mathrm{\beta }= \mathrm{\gamma }= 90°$
2. a = b $\ne$c, $\mathrm{\alpha }= \mathrm{\beta }= \mathrm{\gamma }= 90°$
3. a = b = c, $\mathrm{\alpha }= \mathrm{\gamma }= 90°,$ $\mathrm{\beta }\ne 90°$
4. a $\ne$b $\ne$c, $\mathrm{\alpha }= \mathrm{\beta }= 90°,$ $\mathrm{\gamma }\ne 90°$

1. a, b                                         
2. b, c
3. a, b, c                                     
4. a, c

Among the following types of voids, which one is the largest void-
(1) Triangular system                             
(2) Tetragonal system
(3) Monoclinic system                             
(4) Octahedral

When heated above 916$°$C. iron changes its bcc crystalline form to fcc without the change in the radius atom. The ratio of density o fthe crystal before heating and after heating is:
1. 1.069
2. 0.918
3. 0.725
4. 1.231

The density of solid argon (Ar = 40g/mol) is 1.68 g/mL at 40 K. If the argon atom is assumed to be a sphere of radius $1.50\times {10}^{-8} \mathrm{cm}$, what % of solid Ar is apparently empty space? (Use $\mathrm{N}=6\times {10}^{23}$)
1. 35.64
2. 64.36
3. 74%
4. None of these