The radius of hydrogen atom in the ground state is 0.53 Å . After collision with an electron, it is found to have a radius of 2.12 Å , the principal quantum number n of the final state of the atom is

Step-by-step solution

Given, radius of H -atom in the ground state (n₁=1 ) r₁=0.53 Å Radius of excited state (n₂ ) r₂=212 Å We know that, r n^2 array ll & r₁ r₂ = ( n₁ n₂ )^2 0.53 212 = ( 1 n₂ )^2 [ n₁=1 ] & 1 4 = 1 n₂^2 ( 1 2 )^2= 1 n₂^2 n₂=2 i.e. & n n=2 array