Explain why a test tube immersed at a certain angle in a tumbler of water appears to have a mirror suface for a certain viewing position? `(AS_(7))`

In a certain region of space, electric field is along the z-direction throughout. The magnitude of electric field is, however, not constant but increases uniformly along the positive z- direction, at the rate of 10^5 NC^(-1) per metre. What are the force and torque experienced by a system having a total dipole moment equal to 10^(-7) Cm in the negative Z-direction?