A ray of light with wavelength $\lambda$ is incident on three different photoelectric cells namely 1, 2 and 3. The threshold wavelength of these photoelectric cells are $\lambda_{1}$, $\lambda_{2},$ and $\lambda_{3,}$ respectively and the magnitude of stopping potentials of these cells are $V_{1}$, $V_{2}$ and $V_{3},$ respectively. The relation between $\lambda$ and threshold wavelengths are $\lambda_{1}\lambda$ and $\lambda_{3}>>\lambda$. The correct option is:

The lens combination as shown in the figure, consists of two lenses, $L_{1}$ and $L_{2}$, of the focal lengths +10 cm and -10 cm, respectively. The position of the image formed is: [Image Placeholder]

Consider the following nuclear reaction ${}^{238}U\longrightarrow{}^{234}Th+{}^{4}He$. Take masses of ${}^{238}U$, ${}^{234}Th$ and ${}^{4}He$ as 238.050 u, 234.043 u and 4.003 u, respectively. The Q value for the reaction, in keV, is: [Given: $1~u=931.5~MeV~c^{-2}$]

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Forelimbs of human and bats are homologous. Reason R: Forelimbs of humans and bats have similar anatomical structure. In the light of the above statements, choose the most appropriate answer from the options given below.

Bob B of mass m at rest is hanging vertically from the ceiling via a massless string of length 10 m, as shown in the figure. Point mass A of mass m travelling horizontally with speed $10~ms^{-1}$ hits bob B elastically. The bob B rises h meter after the collision. Taking the acceleration due to gravity $g=10~ms^{-2}$ and neglecting the size of the bob, the value of h is: [Image Placeholder]