In a permanent magnet at room temperature
A. magnetic moment of each molecule is zero.
B. the individual molecules have a non-zero magnetic moment which is all perfectly aligned.
C. domains are partially aligned.
D. domains are all perfectly aligned
The answer is the option (d)
Permanent magnet behaves like a ferromagnetic substance at room temperature and in the absence of an external magnetic field, the domains are spread randomly. However, when put in a magnetic field, the domains are arranged to align with the external field and even when the magnet is taken out of the field, the domains stay intact.