WBJEE 2024 Physics & Chemistry Paper

When a convex lens is placed above an empty tank, the image of a mark at the bottom of the tank, which is 45 cm from the lens is formed 36 cm above the lens. When a liquid is poured in the tank to a depth of 40 cm , the distance of the image of the mark above the lens is 48 cm . The refractive index of the liquid is