Dual Nature of ...

What is the wavelength $$(\mathring{ A } )$$ of a photon that has an energy of $$4.38 \times 10^{-18}$$ J?

A subatomic particle of mass $$10^{-18} \mu g$$ is in thermal equilibrium with its surrounding at temperature of 400 K. Then the wave length of this particle will be

An element undergoes a reaction as shown: $$X+2e^− \to X^{ 2−}$$ 
Energy released = 30.87 eV/ atom. If the energy released, is used to dissociate 4 g of $$H_2$$ molecules, equally into $$H^{+}$$ and$$H^{*}$$, where $$H^{*}$$ is excited state of H atoms where the electron travels in orbit whose circumference equal to four times its de Broglie's wavelength. Determine the least moles of X that would be required :
Given : I.E of H = 13.6 eV/atom, bond energy of $$H_2$$ = 4.526 eV /molecule.

The frequency of line spectrum of sodium is $$5.09\times 10^{14} sec^{-1}$$. Its wavelength ( in nm) will be -[ $$C=3\times 10^8 $$m/sec]

The accelerating potential that must be imparted to a proton beam to given it an effective wavelength of 0.05 nm is
(At. of proton = 1.008 g)

A metal have work function 4 eV is exposed to photon of $$\lambda =1240\AA .$$ If a accelerating potential of 7.6 volt is applied, then the electron with maximum kinetic energy will have speed equal to  

If $$E_e, E_a$$, and $$E_p$$ represents the kinetic energies of an electron alpha particle and a proton respectively, each moving with same De-Broglie wavelength then :

When the light of frequency 2$${ v }_{ 0 }$$(where $${ v }_{ 0 }$$ is the threshold frequency), is incident on a metal plate the maximum velocity of electrons emitted is $${ v }_{ 1 }$$ .When the frequency of the incident radiation is increased to 5$${ v }_{ 0 }$$.The maximum velocity of electrons emitted from the same plate is $${ v }_{ 2 }$$.The ratio of $${ v }_{ 1 } to { v }_{ 2 }$$ is 

When electron are de-exciting from nth orbit of hydrogen atoms, 15 spectral lines are formed. The shortest wavelength among these wil be

A photon of wavelength $$6200A^{o}$$ was incident on a metal whose threshold frequency was $$12400A^{o}$$ cal the $$kE$$ with which electron was emited?