The graph between (1)/(u) and (1)/(v) for a thin convex lens in...

For point $B, \dfrac{1}{u} = - 0 . 10{cm}^{- 1}, \dfrac{1}{v} = 0$

$∴$ Thus, $u = - 10cm, v = \infty$

Using lens formula,

$\dfrac{1}{f} = \dfrac{1}{v} - \dfrac{1}{u} = 0 - \left(- 10\right)$

$⇒ f = 10cm$

Now, using Lens maker's formula,

$\dfrac{1}{f} = \left(\mu - 1\right)\left(\dfrac{1}{{R}_{1}} - \dfrac{1}{{R}_{2}}\right)$, where, $\mu$ is refractive index of lens.

$⇒ \dfrac{1}{10cm} = \left(1 . 5 - 1\right)\left(\dfrac{2}{R}\right) = \dfrac{1}{R} ⇒ R = 10cm$