Terminal Velocity question from NEET 2026 (Re-neet)

Answer: (b)

1. Terminal velocity: $v = \dfrac{2r^2(\sigma - \rho)g}{9\eta} = \dfrac{2r^2\rho g}{9\eta}\left(\dfrac{\sigma}{\rho} - 1\right)$.
2. For the same radius and liquid, $v$ is a linear function of $\sigma/\rho$.
3. $v = 0$ at $\sigma/\rho = 1$ and $v$ rises as a straight line for $\sigma/\rho > 1$ (the ball sinks).
4. So the answer is (b): a straight line starting from zero at $\sigma/\rho = 1$.