In Young's double slit experiment the y-coordinates of central maxima and 10^th maxima are 2 cm and 5 cm respectively. When the YDSE apparatus is immersed in a liquid of refractive index 1.5 the corresponding y-coordinates will be

2 cm, 4 cm

Fringe width β ∝ λ. Therefore, λ and hence β decreases 1.5 times when immersed in liquid. The distance between central maxima and 10^th maxima is 3 cm in vacuum. When immersed in liquid it will reduce to 2 cm. Position of central maxima will not change while 10^th maxima will be obtained at y = 4 cm.