Which of the following is not ferromagnetic ?

Options

A. `Mn^(4+)`
B. `Ti^(4+)`
C. Co
D. both (1) and (2)

Answer

D

Explanation

The metals iron, cobalt, nickel, and certain alloys are vastly more magnetic than any other known substance: these metals are said to be ferromagnetic. Ferromagnetism is due to unbalanced electron spin in the inner electron orbits of the elements concerned which gives the atom a resultant magnetic moment. The ionic spacing in ferromagnetic crystals is such that very large forces, called exchange force, cause the alignment of all the individual magnetic moments of large groups of atoms to given highly magnetic domains. In an unmagetized piece of ferromagnatic material such as iron, these domains are orignment at random, their magnetic axes pointing in all direction. The application of an extrenal field serves to line up the domain axes, giving rise to the observed magnetism. Ferromagnetic substance have very large magnetic permeabilities, which vary with the strength of the applied field. A given ferromagnetic substance loses its ferromagnetic properties at a certain critical temperature, the curie temperature for the substance. `Mn^(4+) (3d^(3))` is paramagnetic due to unpaired electrons while `Ti^(4+) (3d^(0))` is diamagnetic due to paired spins.