Statement I By increasing the potential difference between cathode and anode continuously in a photoelectric experiment, the photocurrent always increases continuously.

Statement II If two photons $A$ and $B$ of energies 2.5 eV and 3.5 eV respectively, fall on a metal surface of work function 2.0 eV , then the ratio of maximum kinetic energies emitted between $A$ and $B$ is 3 .

Statement III The maximum energy needed by an electron to come out from a metal surface is called the work function of the metal.

Which of the following is correct?

Which of the following has the largest de-Broglie wavelength?

In a photoelectric experiment, the wavelength of the light incident on the metal is changed from 200 nm to 400 nm . The decrease in the stopping potential is close to

[use $h c=1240 \mathrm{eV}$-nm, where $h=$ Planck's constant and $c$ is velocity of light]

The de-Broglie wavelength of an electron with kinetic energy of 320 eV is (take, $h=6.0 \times 10^{-34}$ SI unit, mass of electron $=m_c=9.0 \times 10^{-31} \mathrm{~kg}$, charge of an electron $=1.6 \times 10^{-19} \mathrm{C}$ )