Two charges each equal to $2\,\mu C$ are $0.5\,m$ apart. If both of them exist inside vacuum, then the force between them is.......$N$

Two small conducting spheres of equal radius have charges $ + 10\,\mu C$ and $ - 20\,\mu C$ respectively and placed at a distance $R$ from each other experience force ${F_1}$. If they are brought in contact and separated to the same distance, they experience force ${F_2}$. The ratio of ${F_1}$ to ${F_2}$ is

Consider three point objects $P, Q$ and $R \cdot P$ and $Q$ repel each other, while $P$ and $R$ attract. What is the nature of force between $Q$ and $R$ ?

Two electrons are separated by a distance of $1\,\mathop A\limits^o $. What is the coulomb force between them

Assertion : Consider two identical charges placed distance $2d$ apart, along $x-$ axis. The equilibrium of a positive test charge placed at the point $O$ midway between them is stable for displacements along the $x-$ axis.

Reason: Force on test charge is zero

Why Coulombian force is called two body force ?