61. The dependences of the magnetic susceptibility $$\left( \chi \right)$$ of a material with temperature (T) can be represented by $$\chi \propto \frac{1}{{T - \theta }},$$ where θ is the Curie-Weiss temperature. The plot of magnetic susceptibility versus temperature is sketched in the figure, as curves P, Q and R with curve Q having θ = 0. Which one of the following statements is correct?
62. In a crystal of N primitive cells, each cell contains two monovalent atoms. The highest occupied energy band of the crystal is
63. For a closed packed bcc structure of hard spheres, the lattice constant a is related to the sphere radius R as
64. Match the following and choose the correct combination:
Group 1 (Characteristic)
Group 2 (Element)
P. Atomic configuration 1s2, 2s2 2p6, 3s2 3p6
1. Na
Q. Strongly electropositive
2. Si
R. Strongly electronegative
3. Ar
S. Covalent bonding
4. Cl
| Group 1 (Characteristic) | Group 2 (Element) |
| P. Atomic configuration 1s2, 2s2 2p6, 3s2 3p6 | 1. Na |
| Q. Strongly electropositive | 2. Si |
| R. Strongly electronegative | 3. Ar |
| S. Covalent bonding | 4. Cl |
65. Two dielectric materials A and B exhibit both ionic and orientational polarizabilities. The variation of their susceptibilities $$\chi \left( { = {\varepsilon _r} - 1} \right)$$ with temperature T is shown in the figure, where $${\varepsilon _r}$$ is the relative dielectric constant. It can be inferred from the figure that
66. If the static dielectric constant of NaCl crystal is 5.6 and its optical refractive index is 1.5, the ratio of its electric polarizability to its total polarizability is
67. In an insulating solid which one of the following physical phenomena is consequence of Pauli's exclusion principle?
68. The energy of a ferromagnet as a function of magnetization M is given by F(M) = F0 + 2(T - Tc) M2 + M4, F0 > 0
The number of minima in the function F(M) for T > Tc is
The number of minima in the function F(M) for T > Tc is