A compound is formed by two elements X and Y. Atoms of the element Y (as anions) make ccp and those of the element X (as cations) occupy all the octahedral voids. The formula of the compound is-

1. X₂Y₃
2. XY₃
3. XY
4. X₂Y

Atoms of element B form hcp lattice and those of the element A occupy 2/3rd of tetrahedral voids. The formula of the compound formed by the elements A and B is :
1. A₂B₃
2. A₄B₃
3. A₄B
4. AB₃

An element has a body-centred cubic (bcc) structure with a cell edge of 288 pm. The density of the element is 7.2 g/cm³. The number of atoms present in 208 g of the element are
1. 14.16×10²¹ atoms
2. 24.16×10²¹ atoms
3. 14.16×10²³ atoms
4. 24.16×10²³ atoms

X-ray diffraction studies show that copper crystallizes in an fcc unit cell with cell edge of 3.608×10^-8 cm. In a separate experiment, copper is determined to have a density of 8.92 g/cm³ . It can be concluded from the given data that the atomic mass of copper is :
1. 61.1 u
2.  63.1 u
3. 122.2 u
4. 126.1 u

Silver forms ccp lattice and X-ray studies of its crystals show that the edge length of its unit cell is 408.6 pm. The density of silver (Atomic mass = 107.9 u) is-

1. 10.5 g cm^-3
2. 9.5 g cm^-3
3. 11.5 g cm^-3
4. 12.5 g cm^-3