Answer:
This is a conceptual problem so I will try my best to explain the impossible scenario. First of all the two dust particles ara virtually exempt from any external forces and at rest with respect to each other. This could theoretically happen even if it's difficult for that to happen. The problem is that each of the particles have an electric charge which are equal in magnitude and sign. Thus each particle should feel the presence of the other via a force. The forces felt by the particles are equal and opposite facing away from each other so both charges have a net acceleration according to Newton's second law because of the presence of a force in each particle:

Having seen Newton's second law it should be clear that the particles are actually moving away from each other and will not remain at rest with respect to each other. This is in contradiction with the last statement in the problem.
Without knowing anything about their magnitudes or directions, the only thing you can always say about thier combination is that it's the "net force" on the object.
C) Natural and Artificial sources
Answer:
The horizontal distance covered by the firework will be 
Explanation:
Let acceleration due to gravity on the planet be g, initial velocity of the firework be u and angle made with the horizontal be ∅.
writing equation of motion in vertical direction:


and 
therefore 
writing equation of motion in horizontal direction:


therefore the equation becomes 
therefore horizontal distance traveled =
Answer:
For an atom to have a balanced charged, the number of protons shall be equal to the number of electrons of an atom. proton is the positive part of an atom whereas electrons are the negative part of an atom. Only if the number of protons will be equal to the number of electron, the atom will be able to be neutral.
If the number of electron will be more, then the atom will be negative. If the number of electron will be less, then the atom will be positive.