question_answer

Which of the transitions in hydrogen atom emits a photon of lowest frequency (n = quantum number)

A) \[n= 2 to\,\,n =1\]         

B) \[n =4 to\,\,n = 3\]

C) \[n= 3 \,to\,\,n = 1\]      

D) \[n = 4\,\,to\,\,n = 2\]

Correct Answer: B

Solution :

\[{{E}_{1}}\,\,=\,\,-13.6-(-\,3.4)=-10.2\,\,eV\] \[{{E}_{2}}\,\,=\,\,-13.6-(-\,1.51)=-12.09\,\,eV\] \[{{E}_{3}}\,\,=\,\,-1.51-(-\,0.85)=-0.66\,\,eV\] \[{{E}_{4}}\,\,=\,\,-3.4-(-1.51)=-1.89\,\,eV\] \[{{E}_{3}}\] is least, i.e., frequency is lowest.