Answer
Please see the work below.
Work Step by Step
We know that if the experiment is performed in water, then the refractive index is changed from air to water and the wavelength decreases to $\frac{\lambda}{n}$. The condition for the white fringe is $ dsin\theta=m\lambda $. Thus, the wavelength is directly proportional to angles of all bright fringes and as the wavelength is reduced, hence the angles of all the bright fringes will decrease and the fringes will be tightly packed.
