Dual Nature Of Radiation And Matter

What is the de Broglie wavelength associated with an elector accelerated through a potential difference of 144 V?

Which of the following statements are correct?
A. Number of photoelectrons emitted per second is directly proportional to the intensity of incident radiation
B. Cut off potential is the minimum negative potential given to the plate for which photocurrent becomes maximum
C. For a given frequency of the incident radiation, the stopping potential is independent of its intensity
D. Even for the exceedingly dim incident radiation apparent time lag is~ 109s or less
E. Photons are electrically neutral and are not deflected by electric and magnetic fields
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Choose the correct statements from the following:
A. The minimum energy required to free the electron from the ground state of the hydrogen atom is 13.6 J
B. The principle quantum number n labels the stationary states in the ascending order of energy
C. Bohr gave the basic idea of discrete energy levels
D. de Broglie hypothesis provided an explanation for Bohr's second postulate for the quantization of angular momentum of the orbiting electron
E. line spectrum provides useful information about the atomic structure.
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Find the ratio of de-Broglie wavelengths of deuteron having energy E and -particle having energy 2E :