A convex lens has power $P$. It is cut into two halves along its principal axis. Further one piece (out of the two halves) is cut into two halves perpendicular to the principal axis (as shown in figures). Choose the incorrect option for the reported pieces.

The speed of light in media $A$ and $B$ are $2.0\times {10}^{10} \mathrm{cm} {\mathrm{s}}^{-1}$ and $1.5\times {10}^{10} \mathrm{cm} {\mathrm{s}}^{-1}$ respectively. A ray of light enters from the medium $B$ to $A$ at an incident angle $\theta$. If the ray suffers total internal reflection, then

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 lens is $1.5$ and its both the surfaces have same radius of curvatures $R$. The value of $R$ will be _____ $\mathrm{cm}$.

(Where $u=$ object distance, $v=$ image distance)