Magnetism and M...

Permanent magnet has properties retentivity and coercivity respectively as:

A current carrying loop is placed in a uniform magnetic field in four different orientations I, II, III and IV as shown in figure. Arrange them in decreasing order of potential energy.

Magnetic susceptibility of diamagnetic materials is of the order of (SI units) :

The magnetic moment $$ ( \mu ) $$ of a revolving electron around the nucleus varies with principal quantum number $$n$$ as :

A.  Ferromagnetic materials will lose their magnetism if heated above a point known as the Curie temperature.
B. You would have to re-magnetize the magnet again, either in a solenoid or with another permanent magnet, in order to restore the magnetism.
C. If you heat a magnet up a little bit, it will lose some of its magnetism, but on returning to room temperature full magnetism can be restored. 
Which among the following is/are true?

A bar magnet is allowed to fall vertically through a copper coil placed in a horizontal plane. The magnet falls with a net acceleration

The magnetic moment of electron due to orbital motion is proportional to
($$n =$$ principal quantum number)

0.8 J work is done in rotating a magnet by $$60^o$$, placed parallel to a uniform magnetic field. How much work is done in rotating it $$30^o$$ further?

Curie-Weiss law is obeyed by iron.

Two identical coaxial coils $$P$$ and $$Q$$ carrying equal amount of current in the same direction are brought nearer. The current in