Problem 85
In a cubic closed packed structure of mixed oxides, the lattice is made up of oxide ions, \(20 \%\) of tetrahedral Voids are occupied by divalent \(\mathrm{A}^{2+}\) ions and \(50 \%\) of the octahedral voids by trivalent \(\mathrm{B}^{3+}\). The formula of the oxide is? (a) \(\mathrm{A}_{4} \mathrm{~B}_{5} \mathrm{O}_{10}\) (b) \(\mathrm{A}_{2} \mathrm{~B}_{5} \mathrm{O}_{5}\) (c) \(\mathrm{A}_{2} \mathrm{BO}\) (d) \(\mathrm{A}_{4} \mathrm{~B}_{5} \mathrm{O}_{8}\)
Problem 86
A compound formed by elements A and B crystallizes in cubic structure where \(\mathrm{A}\) atoms are at the corners or a cube and \(\mathrm{B}\) atoms are at the face centre. The formula of the compound is (a) \(\mathrm{AB}\) (b) \(\mathrm{AB}_{2}\) (c) \(\mathrm{AB}_{3}\) (d) \(\mathrm{AB}_{4}\)
Problem 87
The radius of \(\mathrm{Ag}^{+}\)ion is \(126 \mathrm{pm}\) while that of \(\mathrm{I}\) ion is \(216 \mathrm{pm}\). The coordination number of \(\mathrm{Ag}\) in \(\mathrm{AgI}\) is (a) 8 (b) 6 (c) 4 (d) 2
Problem 88
Which of the following crystals have \(6: 6\) coordination? (a) \(\mathrm{MnO}\) (b) \(\mathrm{NH}_{4} \mathrm{I}\) (c) \(\mathrm{ZnS}\) (d) none of these
Problem 89
\(\mathrm{TiO}_{2}\) (rutile) shows \(6: 3\) coordination. The solid having rutile like structure among the following is (a) \(\mathrm{KCl}\) (b) \(\mathrm{SnO}_{2}\) (c) \(\mathrm{ZnS}\) (d) none of these
Problem 90
\(\mathrm{M}_{2} \mathrm{X}\) have a structure closely related to that of fluorite. It is actually reverse of fluorite structure hence called antifluorite structure. In such a structure (a) \(\mathrm{F}\) ions occupy all the 8 octahedral voids (b) each \(\mathrm{F}^{-}\)is surrounded by \(4 \mathrm{Ca}^{2+}\) in tetrahedral arrangement (c) larger cations occupy the position of \(\mathrm{F}\) - ions and smaller anions that of \(\mathrm{Ca}^{2+}\) ions. (d) smaller cations occupy the position of fluoride ions and larger anions that of \(\mathrm{Ca}^{2+}\) ions
Problem 91
The number of atoms per unit cell in a BCC, a FCC and a simple cubic cell are respectively (a) \(1,4,2\) (b) \(2,4,1\) (c) \(4,1,2\) (d) \(4,2,2\)
Problem 93
The number of atoms per unit cell in a simple cubic, face-centred cubic and body-centred cubic are....... respectively (a) \(1,2,4\) (b) \(1,4,2\) (c) \(4,2,1\) (d) \(1,4,3\)
Problem 94
Amorphous substances show (i) short and long range order (ii) short range order (iii) long range order (iv) have no sharp melting point (a) (i) and (ii) are correct (b) (ii) and (iv) are correct (c) (ii), (iii) and (iv) are correct (d) (i) and (iv) are correct
Problem 95
A compound contains two types of atoms: \(\mathrm{X}\) and \(\mathrm{Y}\). It crystallizes in a cubic lattice with atoms \(\mathrm{X}\) at the corners of the unit cell and atoms \(\mathrm{Y}\) at the body centres. The simplest possible formula of this compound is: (a) XY (b) \(\mathrm{X}_{2} \mathrm{Y}_{2}\) (c) \(\mathrm{XY}_{6}\) (d) \(\mathrm{X}_{\mathrm{g}} \mathrm{Y}\)
