Ferrous oxide has a cubic structure and each edge of the unit cell is 5.0. Assuming density of the oxide as 4.0 g/cm-3, then the number of Fe2+ and O2- ions present in each unit cell will be


Correct option is

FourFe2+ and four O2-


Let the units of ferrous oxide in a unit cell = n. Molecular weight of ferrous oxide (FeO)

                          = 56 + 16 = 72g mol-1

Weight of n unit =     

Volume of one unit = (length of corner)3 




                                            = 4.27 = 4



An element occurring in the bcc structure has 12.08 × 1023 unit cells. The total number of atoms of the elements in these cells will be


The number of sphere contained (i) in one body centred cubic unit cell and (ii) in one face centred cubic unit cell, is


CsBr crystal has bcc structure. It has an edge length of 4.3. the shortest interionic distance between Cs+ and Br –  ions is



The number of atoms in 100 g of an fcc crystal with density,

d = 10g/ cm3 and cell edge equal to 100 pm, is equal to


The number of unit cell in 58.5 g of NaCl is nearly


Analysis shows that an oxide ore of nickel has formula Ni0.98O1.00. The percentage of nickel as Ni3+ ions is nearly


In orthorhombic, the value of a, b and c are respectively 4.2, 8.6 and8.3. given the molecular mass of the solute is 155 g mol-1 and that of density is 3.3 g/cc, the number of formula units per unit cell is


A solid has a structure in which ‘W’ atoms are located at the corner of a cubic lattice ‘O’ atoms at the centre of edge and Na atoms at the centre of the cube. The formula for the compound is


In a solid ‘AB’ having the NaCl structure, ‘A’ atoms occupy the corners of the cubic unit cell. If all the face – centred atoms along one of the axes are removed thye the resultant stoichiometry of the solid is


The following is not a function of an impurity present in a crystal