A large number of hydrogen atoms have electrons excited to the nh=4.How many possible spectral lines can appear in the emission spectrum as a result of the electron reaching the ground state(n1=1)?Draw a diagram to show all path ways for the de-excitation from nh=4 ton1=1.

Answer 1

Here:
https://www.google.com/search?q=hydrogen+radiation+spectrum+transitions&tbm=isch&tbo=u&source=univ&sa=X&ved=0CEwQsARqFQoTCO_83vy_08cCFcgyPgodLu8DCw&biw=1920&bih=971#imgrc=84jXbb3JhPIc3M%3A

Look at all possible ways from 4 down to 1 such as
4 - 3 - 2 - 1
or
4 - 2 -1

Answer 2

http://www.google.com/search?q=hydrogen+radiation+spectrum+transitions&tbm=isch&tbo=u&source=univ&sa=X&ved=0CEwQsARqFQoTCO_83vy_08cCFcgyPgodLu8DCw&biw=1920&bih=971#imgrc=84jXbb3JhPIc3M%3A