An ion with mass number 37 possesses one unit of negative charge. If the ion contains 11.1% more neutrons then the electrons, find the symbol of the ion.    


Correct option is


Suppose number of electrons in the ion =    


No. of electrons in  the neutral in atom = x + 1

∴ No. of electrons = x – 1  

Mass number = No. of neutrons + No. of photons  


∴ No. of photons = Atomic no. = x – 1 = 18 – 1 = 17      

Hence, the symbol of the ion will be .




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) 


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?



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.  


A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57 μm. Calculate the rate of emission of quanta per second.


What is the wavelength of the light emitted when the electron in a hydrogen atom undergoes transition from an energy level with n = 4 to an energy level with n = 2? What is the colour corresponding to this wavelength? (Rydberg constant = 109,677 cm–1  


A certain particle carries 2.5 × 10–16 C of static electric charge. Calculate the number of electrons present in it.


An ion with mass number 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. Assign the symbol to this ion.


Nitrogen laser produces a radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 1024, calculate the power of this laser.


The angular momentum of an electron in Bohr’s orbital of hydrogen atom is 4.22× 10–34 kg m2s–1. Calculate the wavelength of the spectral line when the electron falls from this level to the next lower level.    


With what velocity must an electron travel so that its momentum is equal to that of a photon of wavelength 560 nm?