What is the transition in the hydrogen spectrum would have the same wavelength as the Balmer transition, n = 4 to n = 2 of He+ spectrum?


Correct option is

n = 2 to n = 1


For H-like particle in general


∴ For He+ spectrum, for Balmer transition, n = 4 to n = 2.  


For hydrogen spectrum  


Which can be so for n1 = 1 and n2 = 2, i.e., the transition is from

n = 2 to n = 1. 



The ionization energy of hydrogen in excited state is +0.85 eV. What will be the energy of the photon emitted when it returns to the ground state?



Calculate the wavelength associated with an electron

(mass 9.1 × 10–31 kg) moving with a velocity of 103 m sec–1

(h = 6.6 × 10–34 kg m2 sec–1)


What will be the wavelength of a ball of mass 0.1 kg moving with a velocity of 10 ms–1?


Calculate the mass of a photon with wavelength 3.6 Å.


A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1 Å. What is the uncertainty involved in the measurement of its velocity?  



Calculate the uncertainty in the velocity of a wagon of mass 3000 kg whose position is known to an accuracy of ±10 pm

(Planck’s constant = 6.63 × 10–34 Js) 


Calculate the uncertainty in the position of an electron if the uncertainty in its velocity is 5.7 × 105 m/sec (h = 6.6 × 10–34 kg m2 s–1, mass of the electron = 9.1×10–31 kg).


A golf ball has a mass of 40 g and a speed of 45 m/s. If the speed can be measured within accuracy of 2%, calculate the uncertainty in position.



If an electron is moving with a velocity 600 ms–1 which is accurate upto 0.005%, then calculate the uncertainty in its position. 

  (h = 6.63 × 10–34 Js, mass of electron = 9.1 × 10–31 kg) 



Calculate the energy required for the process

           He+ (g) → He2+ (g) + e   

The ionization energy for the H atom in the ground state is

 2.18 × 10–18 J atom–1.