Magnetism and Matter

The ratio of the magnetic moment of two short magnets when they give zero deflection in $$\tan B$$ position when placed at $$12 cm$$ and $$18 cm$$ from centre of a deflection magnetometer is :

Two magnets have their moments of inertia in the ratio $$1 : 4$$; magnetic moments in the ratio $$4 : 9$$. They are vibrating in the same magnetic field of induction $$0.4 gauss$$. If the time period of first magnet is $$0.9 sec$$. The period of oscillation of $$2^{nd}$$ magnet is :

Which metal is used to make ferromagnets ?
At a neutral point,
State whether true or false :
An electromagnet requires a continuous supply of current to maintain the magnetic field.