## Question

### Solution

Correct option is

M2A3

In hexagonal close packing on sphere is in contact with 12 sphere. Thus,

The number of anion A pre unt cell = 12

Octahedral voids = Number of sphere = 12

∴  No. of M atoms per unit cell  of octahedral voids

= 8

⇒                  A : M = 12 : 8 = 3 : 2

∴  The formula of the compound is M2A3.

#### SIMILAR QUESTIONS

Q1

The X-ray power pattern of potassium chloride shows a cone at θ = 90o, using X-ray of wavelength 1.54 × 10–8 cm. What is the spacing between the planes?

Q2

When an electron in an excited Mo atom falls from L to K, shell, an X-ray is emitted. These X-ray are diffracted at angle of 7.75 by planes with a separation of 2.64 Å. What is the difference in energy between K-shell and L-shell in Mo assuming a first order diffraction (sin 7.75 = 0.1349)?

Q3

A compound formed by elements A and B crystallises in cubic structure where B atoms are at the corner of a cube and A atoms at the face centre. The formula of the compound is

Q4

Match box belongs to

Q5

In a crystalline solid, having formula AB2O4, oxide ions are arranged in cubic close packed lattice while cations A are present in tetrahedral voids and cations B are present in octahedral voids. The percentage of tetrahedral voids occupied by A is

Q6

Ag metal crystallises in a cubic closest packed arrangement with the edge of the unit cell having a length a = 407 pm. The radius of the similar atom is

Q7

The density of solid argon is 1.65 g/mL at –233oC. If the argon atom is assumed to be sphere of radius 1.54 × 10–8 cm, what percentage of solid argon is apparently empty space?(At wt of Ar = 40).

Q8

A compound CuCl has fcc structure. Its density is 3.4 g cm–3, what is the length of unit cell?

Q9

A metal crystallizes into two cubic phases fcc and bcc whose unit cell lengths are 3.5 and 3.0 Å respectively. What is the ratio of densities of fcc and bcc?

Q10

The radius of a divalent cation M2+ is 94 pm and that of divalent anion X2–is 146 pm. Thus, M2+ X2– has