## Question

### Solution

Correct option is

8, 4

The Ca2+ ions are arranged in (ccp) arrangement, ie, Ca2+ ions are present at all corner and the centre of each face of the cube. The fluoride ions occupy all the tetrahedral sites. This is 8:4 arrangements, ie, Ca2+ ion is surrounded by 8F- ions and each F- ion by four Ca2+ ions.

#### SIMILAR QUESTIONS

Q1

For an ionic crystal of the general formula AX and coordination number 6, the value of radius ratio will be

Q2

In A+ B- ionic compound, radii of A+ and B- ions are 180 pm and 187 pm respectively. The crystal structure of this compound will be

Q3

Sodium metal crystallizes as a body centred cubic lattice with the cell edge 4.29 . What is the radius of sodium atom?

Q4

An fcc lattice has a lattice parameter a = 400 pm. Calculate the molar volume of the lattice including all the empty space.

Q5

The structure of Na2O crystal is

Q6

Structure similar to zinc blende is found in

Q7

The number of equidistance oppositely charged ions in a sodium chloride crystal is

Q8

What is the coordination number of sodium in Na2O?

Q9

In zinc blende structure, the coordination number of Zn2+ ion is

Q10

When a certain crystal was studied by the Bragg technique using X – rays of wavelength 229 pm, an X – ray reflection was observed at an angle of 230 20’. What is the corresponding interplanar spacing? [sin (23020’) = 0.396]