According to the particle theory of light (Newton's corpuscular theory),what is the velocity of light in a dense medium compared to that in a rare medium?

In the following arrangement $y = 1.0\ mm$,$d = 0.24\ mm$ and $D = 1.2\ m$. The work function of the material of the emitter is $2.2\ eV$. The stopping potential $V_0$ needed to stop the photocurrent will be .............. $V$.

When a light source of power $P$ emitting monochromatic light of wavelength $\lambda$ is kept at a distance $r$ from a photosensitive surface of work function $\phi$ and surface area $A$,which of the following is the wrong option?

For a body moving with relativistic speed,if the velocity is doubled,then

In a photoelectric experiment,light of wavelength $800 \ nm$ produces photoelectrons with the smallest de Broglie wavelength of $1 \ nm$. Then the work function of the metal used in the experiment is nearly (in $eV$)

Consider the following statements $A$ and $B$ and identify the correct choice in the given answers.
$A$. Tightly bound electrons of target material scatter $X$-ray photon,resulting in the Compton effect.
$B$. Photoelectric effect takes place with free electrons.