What is a hard ferromagnetic substance?

Identify the false statement regarding the magnetic properties of substances.

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature,then it will show

For which of the following substances, the magnetic susceptibility is independent of temperature?

Consider the following statements regarding paramagnetic substances:
$A$. They are weakly attracted by an external magnetic field.
$B$. They are strongly attracted by an external magnetic field.
$C$. Their magnetic susceptibility $(\chi)$ is small and positive.
$D$. In a non-uniform magnetic field, they move from a region of strong magnetic field to a region of weak magnetic field.
Which of the above statements are correct?

Ferromagnetic materials used in a transformer must have