Question

According to the quantum-mechanical model for the hydrogen atom, which of the following electron transitions would produce light with the longer wavelength: 2p→1s or 3p→1s?

Answer 1

Answer:

$2p\rightarrow 1s$

Explanation:

The energy of transition of $3p\rightarrow 1s$ is greater as compared to $2p\rightarrow 1s$ as there are more quantum levels which leads to more energy.

Also, considering the expression as:

$E=\frac {h\times c}{\lambda}$

Where,  

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

$\lambda$ is the wavelength

Wavelength is inversely proportional to Energy. Thus, the transition which has lower energy corresponds to higher wavelength.

Thus, answer - $2p\rightarrow 1s$