What is the number of atoms in the unit cell of body centred cubic crystal?

• 1

• 3

• 4

• 2

It a compound is formed by X, Y and Z atoms and Z is present on the comers, Y is present $\frac{1}{2}$ tetrahedral voids and X atom in $\frac{1}{2}$ octahedral voids, which of the following will be the molecular formula of the compound?

• X₂Y₄Z

• XYZ₄

• XYZ

• X₂ZY

If in a cubic cell, atoms A present at all comers and atoms B at the centre of each face. What will be the molecular formula of the compound, if all the atoms present on one body diagonal are replaced by atom C?

• A₃B₁₂C

• AB₁₂C₃

• ABC₃

• A₃B₁₂C₄

Which among the following will anisotrophy?

• glass

• plastic

• barium chloride

• wood

The packing efficiency of simple cubic (sc), body centred cubic (bcc) and cubic close packing (ccp) lattices follow the order

• bcc <ccp <sc

• ccp <bcc <sc

• sc <ccp <bcc

• sc <bcc <ccp

The 'number of tetrahedral and octahedral voids in CCP unit cell are respectively

• 4, 8

• 8, 4

• 12, 6

• 6, 12

Element ‘B’ forms ccp structure and ‘A’ occupies half of the octahedral voids, while oxygen atoms occupy all the tetrahedral voids. The structure of bimetallic oxide is:

• AB₂O₄

• A₂B₂O

• A₂BO₄

• A₄B₂O

0.27 g of a long chain fatty acid was dissolved in 100 cm³ of hexane. 10 mL of this solution was added dropwise to the surface of water in a round watch glass. Hexane evaporates and a monolayer is formed. The distance from edge to centre of the watch glass is 10 cm. What is the height of the monolayer ?[Density of fatty acid = 0.9 g cm^-3, π=3]

• 10^-6 m

• 10^-2 m

• 10^-4 m

• 10^-8 m

139.

The structures of beryllium chloride in the solid state and vapour phase, respectively, are :

• Chain and chain

• Chain and Dimeric

• Dimeric and dimeric

• Dimeric and chain

10 mL of 1 mM surfactant solution forms a monolayer covering 0.24 cm² on a polar substrate. If the polar head is approximated as a cube, what is its edge length?

• 2.0 pm

• 0.1 nm

• 2.0 nm

• 1.0 pm