Answer:
d) F
Explanation:
According to columb's law:
"The magnitude of electrostatic force between two charges is directly proportional to the product of magnitude of two charges and inversly proportional to separation between them."
If q₁ and q₂ are magnitude of two charges, d is distance between them and k is dielectric constant, then force F is given by

According to this force exerted on point charge Q is same as that of 3Q, so force point 3Q charge experience is also F
Incompressible. Compressibility is determine by the amount of space between particles in each state.
C because the wave length was longer