When will the convergent nature of a convex lens be less as compared to its nature in air?

$A$ double convex lens has a focal length of $25\; cm$. The radius of curvature of one of the surfaces is double the other. Find the radii if the refractive index of the material of the lens is $1.5$.

$A$ convex lens of focal length $12 \ cm$ is made of glass of refractive index $\mu_g = \frac{3}{2}$. What will be its focal length when immersed in a liquid of refractive index $\mu_l = \frac{5}{4}$? (in $cm$)

Two thin lenses having $R_1$ and $R_2$ as the radii of curvature of their surfaces are kept coaxially together. Their power is proportional to

In an optics experiment,with the position of the object fixed,a student varies the position of a convex lens and for each position,the screen is adjusted to get a clear image of the object. $A$ graph between the object distance $|u|$ and the image distance $|v|$,from the lens,is plotted using the same scale for the two axes. $A$ straight line passing through the origin and making an angle of $45^{\circ}$ with the $x$-axis meets the experimental curve at $P$. The coordinates of $P$ will be

The graph between $\frac{1}{u}$ and $\frac{1}{v}$ for a thin convex lens in order to determine its focal length is plotted as shown in the figure. The refractive index of the lens is $1.5$ and both its surfaces have the same radius of curvature $R$. The value of $R$ will be in $cm$.
(Where $u =$ object distance,$v =$ image distance)