If an electron is present in n = 6 level. How many spectral lines would be observed in case of H atom ...

What arethe differance between "Nodal surface" and "Nodal plane" ?

Nodal Surface : The place find in between two "s" orbitals where the value of electron density is equal to zero called Nodal surface. 

Nodal Plane : The plane for "p" and "d" orbitals where the value of electron density is equal to zero called Nodal Plane. 

Speed of helium atom at 300K is 2.40 x10^2 meter per sec. What is its wave length. (mass number of helium is 4)..

K.E. of the electron is 4.55 x 10^-25 J. Its de Broglie wave length is ...

The wavelength associated with a golf ball weighing 200g and moving at a speed of 5m/h is of the order.