This can be possible by induction, if a negative charge rod is placed near the sphere (at a distance not in touch) than it attracts positive charge inside the sphere towards its side and the negative charges collected on other side and when the surface of sphere connected to earth than the negative charge goes to earth and the sphere remain positively charged.

After earthing a positively charged conductor electrons flow from earth to conductor and if a negatively charged conductor is earthed then electrons flows from conductor to earth. 

As aluminium and copper are metals, their mobile electrons move under the influence of the external field until they reach the surface of the metal and collect there. External electric fields induce surface changes on metal objects that exactly cancel the field within. Since the field applied is same in both case, the induced charge will be the same. Hence, the magnitude of induced charge in the aluminium will be the same as that of copper.

Electric flux is given by  since amount of charge not depends on size and shape so by making radius <  double the amount of charge remain same so electric flux remain same. 

Electric charge, the basic property of matter carried by some elementary particles, such as atoms; ions; electrons; etc, that govern how the particles are affected by an electric or magnetic field.
Electric charge, which can be positive or negative, occurs in discrete natural units and is neither created nor destroyed.

An electric dipole is a separation of positive and negative charges. The simplest example of this is a pair of electric charges of equal magnitude but opposite sign, separated by some (usually small) distance. A permanent electric dipole is called an electret.

An electric dipole is tagged as a pair of objects which possess equal & opposite charges, parted by a significantly small distance.

Since Potential difference between two points in equipotential surfaces is zero , the work done between two points in equipotential surface is also zero .

Only alpha rays are moving with small velocity and having charge so they will be affected by electric field.

Since the charge –q is moving in elliptical orbit so to make its motion stable the total angular momentum of the charge is constant since it experience a centripetal force from the charge +Q so it follow the motion as the motion of earth around sun.

The triboelectric effect (also known as triboelectric charging) is a type of contact electrification in which certain materials become electrically charged after they come into frictional contact with a different material.
Example: Rubbing glass with fur, or a plastic comb through the hair.

When we charge something with static electricity, no electrons are made or destroyed. Electrons are just moved from one place to another. The net electric charge stays the same. This is called the principle of conservation of charge.
i.e. If a glass rod is rubbed with silk, some electrons moves from glass rod to silk no new charge is generated or destroyed. 

If a charge q is placed outside than the electric field lines incident on the conducting sphere , if some charge is developed due to thee lines than opposite surface becomes oppositely charge and the total charge becomes zero.

Acc to coulomb's law unlike charges always attract each other while like charges always repel each other.

It is not possible to remove or add protons/neutrons to an atom, but electrons can be added or removed by an atom easily.
By adding electrons it becomes negatively charged.
By removing electrons it becomes positively charged. 

Suppose in the following figure, equilibrium of charge B is considered. Hence for its equilibrium,

The electrostatic force is an attractive and repulsive force between particles are caused due to their electric charges. The electric force between stationary charged bodies is conventionally known as the electrostatic force. 

where,
x = distance of the null point from the small charge
d = distance between two charges
q₂ = bigger charge
q₁ = small charge
+1 for like charges and -1 for unlike charges

Conductors are materials that permit electrons to flow freely from particle to particle. An object made of a conducting material will permit a charge to be transferred across the entire surface of the object.