Answer:
A. Two protons and two neutrons.
Explanation:
Alpha particles are positively charged specie identical to the nucleus of Helium atom.
Two atoms of the same element can have different numbers of protons
false
diff nos neutrons ... isotopes,
diff protons ... diff elements
Answer:
The correct option is (b).
Explanation:
Given that,
Electric field, 
We need to find the magnitude of the force on the electron as a result of the electric field.
We know that, the electric force is given by :

So, the required force on the electron is equal to
.
The net force on the hanging object is zero. If it were not zero, then the object would be accelerating in some direction.