91Ó°ÊÓ

The element crystallizes in a body centered cubic lattice and the edge of the unit cell is \(0.351\) \(\mathrm{nm}\). The density is \(0.533 \mathrm{~g} / \mathrm{cm}^{3} .\) What is the atomic weight? (a) \(12.0\) (b) \(6.94\) (c) \(9.01\) (d) \(10.8\)

An element \(X\) (At. wt. \(=80 \mathrm{~g} / \mathrm{mol}\) ) having fcc structure, calculate no. of unit cells in \(8 \mathrm{gm}\) of \(X\) : (a) \(0.4 \times N_{A}\) (b) \(0.1 \times N_{A}\) (c) \(4 \times N_{A}\) (d) none of these

Molybdenum (At. wt. = \(96 \mathrm{~g} \mathrm{~mol}^{-1}\) ) crystallizes as bce crystal. If density of crystal is \(10.3 \mathrm{~g} / \mathrm{cm}^{3}\), then radius of Mo atom is (use \(N_{A}=6 \times 10^{23}\) ): (a) \(111 \mathrm{pm}\) (b) \(314 \mathrm{pm}\) (c) \(135.96 \mathrm{pm}\) (d) none of these

The most malleable metals (Cu, Ag, Au) have close-packing of the type : (a) Hexagonal close-packing (b) Cubic close-packing (c) Body-centred cubic packing (d) Malleability is not related to type of packing

The co-ordination number of a metal crystallising in a hexagonal close-packed structure is: (a) 12 (b) 4 (c) 8 (d) 6

If the ratio of coordination no. of \(A\) to that of \(B\) is \(x: y\), then the ratio of no. of atoms of \(A\) to that no. of atoms of \(B\) in unit cell is: (a) \(x: y\) (b) \(y: x\) (c) \(x^{2}: y\) (d) \(y: x^{2}\)

The atomic radius of strontium (Sr) is \(215 \mathrm{pm}\) and it crystallizes with a cubic closest packing. Edge length of the cube is: (a) \(430 \mathrm{pm}\) (b) \(608.2 \mathrm{pm}\) (c) \(496.53 \mathrm{pm}\) (d) none of these

By X-ray diffraction it is found that nickel (at mass \(=59 \mathrm{~g} \mathrm{~mol}^{-1}\) ), crystallizes with ccp. The edge length of the unit cell is \(3.5 \AA\). If density of Ni crystal is \(9.0 \mathrm{~g} / \mathrm{cm}^{3}\). Then value of Avogadro's number from the data is : (a) \(6.05 \times 10^{23}\) (b) \(6.11 \times 10^{23}\) (c) \(6.02 \times 10^{23}\) (d) \(6.023 \times 10^{23}\)

In a hexagonal close packed (hcp) structure of spheres, the fraction of the volume occupied by the sphere is \(A\). In a cubic close packed structure the fraction is \(B\). The relation for \(A\) and \(B\) is : (a) \(A=B\) (b) \(AB\) (d) \(A\) is equal to the fraction in a simple cubic lattice.

The unit cell present in \(\mathrm{ABCABC}\), closest packing of atoms is: (a) hexagonal (b) tetragonal (c) face centered cube (d) primitive cube