Give the differences between charge and mass.

We have three identical metallic spheres $A, B$ and $C$. $A$ is given a charge $Q$,and $B$ and $C$ are uncharged. The following processes of touching of two spheres are carried out in succession. Each process is carried out with sufficient time.
$(i)$ $A$ and $B$
$(ii)$ $B$ and $C$
$(iii)$ $C$ and $A$
$(iv)$ $A$ and $B$
$(v)$ $B$ and $C$
The final charges on the spheres are

Select the correct alternative.

One metallic sphere $A$ is given a positive charge,whereas another identical metallic sphere $B$ of exactly the same mass as $A$ is given an equal amount of negative charge. Then:

The electric charge of an $\alpha$-particle is ..........

Four metal conductors having different shapes:
$1.$ $A$ sphere
$2.$ Cylindrical
$3.$ Pear
$4.$ Lightning conductor
are mounted on insulating stands and charged. The one which is best suited to retain the charges for a longer time is: