# Two large conducting spheres carrying charges $Q_1$ and $Q_2$ are brought close to each other. Is the magnitude of electrostatic force between them exactly given by $\large\frac{Q_1Q_2}{4 \pi \in_0 r^2}$ , where r is the distance between their centres?

No. This is because $Q_1$ and $Q_2$ shall alter due to the effect of electrostatic induction.