Q.

If the atom Fm100257 follows the Bohr model and the radius of Fm100257 is n times the Bohr radius, then find n.                  [2003]

1 100  
2 200  
3 4  
4 14  

Ans.

(4)

For an atom following Bohr's model, the radius of the fifth orbit.

rm=r0m2Z, where r0 = Bohr's radius.

For Fm100257,  m=5  (Fifth orbit in which the outermost electron is present) and Z=100

∴  rm=r0×52100=nr0  (given)

∴  n=14