Statement I : The ferromagnetic property depends on temperature. At high temperature, ferromagnet becomes paramagnet.
Statement II : At high temperature, the domain wall area of a ferromagnetic substance increases. In the light of the above statements, choose the most appropriate answer from the options given below:

Statement I states that ferromagnetic property depends on temperature, and above a certain temperature (the Curie temperature), a ferromagnet becomes a paramagnet. This is correct — it is the well-established Curie temperature phenomenon.

Statement II states that at high temperature, the domain wall area of a ferromagnetic substance increases. This is incorrect. At high temperature, the domains actually break down or become disordered. The thermal energy disrupts the alignment of magnetic moments within domains. Above the Curie temperature, domain structure itself ceases to exist as the material becomes paramagnetic — it is not that domain walls increase in area. In fact, as temperature increases, thermal agitation destroys the long-range magnetic order, causing the domains to shrink and eventually disappear rather than domain walls expanding.

Therefore, Statement I is true but Statement II is false.