Light strikes a metal surface causing photoelectric emission. The wavelength of incident light is 248 nm . If the stopping potential for the ejected electrons is 2.8 eV , then the work function of the metal is (take, $h c=1240 \mathrm{eV}-\mathrm{nm}$ )

The de-Broglie wavelength associated with an electron, accelerated through a potential difference of 121 V is about

(take, Plank's constant $=h=6.6 \times 10^{-34} \mathrm{Js}$, mass of electron $=9 \times 10^{-31} \mathrm{~kg}$ )

The value of planck's constant, if the slope of the graph of stopping potential versus frequency of incident light is $4 \times 10^{-15} \mathrm{~V}$-s is (given charge of an electron $=1.6 \times 10^{-19} \mathrm{C}$ )

For photoelectric effect which of the following statements are true. (I) The kinetic energies of the photoelectrons do not depend on the frequency of light. (II) Photoelectric effect will always occur for highly intense light. (III) The maximum kinetic energy of photoelectron does not depend upon the intensity of the light. (IV) The escaping electron's kinetic energy is larger for larger frequency.