Problem 128
Ice crystallizes in hexagonal lattice. At a given temperature, the density of ice is \(0.92 \mathrm{gcm}^{-3}\). The volume of unit cell is \(1.3 \times 10^{-22} \mathrm{~cm}^{3}\). The number of \(\mathrm{H}_{2} \mathrm{O}\) molecules per unit cell is
Problem 129
Density of Palladium (At wt. \(=106.4\) ) is \(12.0 \mathrm{~g} / \mathrm{cc}\). The unit cell edge length is \(3.9 \times 10^{-8} \mathrm{~cm}\). The effective number of atoms in the unit cell (Avogadro number is \(\left.6 \times 10^{23}\right)\) is
Problem 131
In \(\mathrm{CsCl}\) structure, the number of \(\mathrm{Cs}^{+}\)ions that occupy second nearest neighbor locations of a \(\mathrm{Cs}^{+}\)ion is
Problem 133
The cubic unit cell of aluminium has an edge length of \(400 \mathrm{pm}\). Its density is \(2.8 \mathrm{~g} \mathrm{~cm}^{-3}\). The number of atoms present per unit cell will be . (atomic mass of \(\mathrm{Al}=27)\)
Problem 134
The \(\mathrm{ZnS}\) structure is cubic. The unit cell may be described as a face centered sulphide ion sub-lattice with zinc ions in the centers of alternating mini cubes made by partitioning the main cube into eight equal parts. The sum of the nearest neighbors around each \(\mathrm{Zn}^{2+}\) and \(\mathrm{S}^{2-}\) ion in the unit cell with be equal to
Problem 135
Number of atoms in the unit cell of Na (BCC type crystal) and \(\mathrm{Mg}\) (FCC type crystal) are respectively [2002] (a) 4,4 (b) 4,2 (c) 2,4 (d) 1,1
Problem 136
How many unit cells are present in a cube shaped ideal crystal of \(\mathrm{NaCl}\) of mass \(1.00 \mathrm{~g}\) ? [Atomic mass of \(\mathrm{Na}=\) \(23, \mathrm{Cl}=35.5]\) (a) \(2.57 \times 10^{21}\) (b) \(6.14 \times 10^{21}\) (c) \(3.28 \times 10^{21}\) (d) \(1.71 \times 10^{21}\)
Problem 138
An ionic compound has a unit cell consisting of A ions at the corners of a cube and \(\mathrm{B}\) ions on the centres of the faces of the cube. The empirical formula for this compound would be [2005] (a) \(\mathrm{AB}\) (b) \(\mathrm{A}_{2} \mathrm{~B}\) (c) \(\mathrm{AB}_{3}\) (d) \(\mathrm{A}_{3} \mathrm{~B}\)
Problem 139
Total volume of atoms present in a face-centred cubic unit cell of a metal is \((\mathrm{r}\) is atomic radius) (a) \(\frac{20}{3} \pi \mathrm{r}^{3}\) (b) \(\frac{24}{3} \pi \mathrm{r}^{3}\) (c) \(\frac{12}{3} \pi \mathrm{r}^{3}\) (d) \(\frac{16}{3} \pi \mathrm{r}^{3}\)
Problem 140
In a compound, atoms of element \(\mathrm{Y}\) from ccp lattice and those of element \(\mathrm{X}\) occupy \(2 / 3^{\text {rd }}\) oftetrahedral voids. The formula of the compound will be [2008] (a) \(\mathrm{X}_{4} \mathrm{Y}_{3}\) (b) \(\mathrm{X}_{2} \mathrm{Y}_{3}\) (c) \(\mathrm{X}_{2} \mathrm{Y}\) (d) \(\mathrm{X}_{3} \mathrm{Y}_{4}\)
