Question

Question 10 (1 point) Which of the following transitions will cause the largest wavelength of light to be emitted in a hydrogen atom? 1) n=1 to n = 2 2) n = 5 to n = 1 3) n = 5 to n = 3 O O OO 4) n = 5 to n = 4 5) n = 1 to n = 5

Answer 1

ANSWER : n= 5 to n=4

Light is emitted from Hydrogen atom . We know that, light is emitted when electrons falls from higher energy levels to lower energy levels. Therefore options 1), 5) are incorrect because in these cases electron moves from lower energy level to higher energy level by absorption of light..

We have relation , $\Delta$ E = h C / $\lambda$

Where , $\Delta$ E = E final - E initial , $\lambda$ is wavelength of light , C is velocity of light.

From above equation, wavelength is inversely proportional to difference in energy of energy levels.

i e Smaller the $\Delta$ E , larger will be wavelength .

We know that, $\Delta$ E ( n=5 to n = 4) < $\Delta$ E ( n=5 to n = 3) <  $\Delta$ E ( n=5 to n = 2) < $\Delta$ E ( n=5 to n = 1)

From this, $\Delta$ E for transition n=5 to n=4 is small compared to transitions n= 5 to n= 3 , n= 5 to n = 2 and n=5 to n= 1

Hence, from above relationship it is clear that light of largest wavelength will be emitted for transition n=5 to n=4..