Explanation:

The energy levels in the hydrogen atom are discrete and quantized. When the electron moves from a higher energy level to a lower energy level, it emits a photon of specific wavelength, which can be observed as a spectral line in the emission spectrum.

Formula:

The energy of a photon can be calculated using the formula:

E = hc/λ

Where E is the energy of the photon, h is Planck's constant, c is the speed of light, and λ is the wavelength of the photon.

Calculation:

In the hydrogen atom, the energy levels are given by the formula:

En = -13.6/n^2 eV

Where En is the energy of the nth level, and n is the principal quantum number.

From this formula, we can see that the energy levels are inversely proportional to the square of the principal quantum number.

The energy difference between two energy levels can be calculated using the formula:

ΔE = Efinal - Einitial

Where ΔE is the energy difference, Efinal is the final energy level, and Einitial is the initial energy level.

The wavelength of the emitted photon can be calculated using the formula:

λ = hc/ΔE

Where λ is the wavelength of the emitted photon, h is Planck's constant, c is the speed of light, and ΔE is the energy difference between the two energy levels.

Answer:

The number of lines in the emission spectrum of hydrogen atom can be calculated using the formula:

n = (n^2 - n)/2

Where n is the number of energy levels.

In the case of hydrogen atom, n = 6.

Substituting the value of n in the formula, we get:

n = (6^2 - 6)/2 = 15

Therefore, there are 15 spectral lines in the emission spectrum of hydrogen atom in the ultraviolet region.

I think 15 is the right answer because there are 6 energy levels in H atom and is in Lyman series.so n2 is 6 and n1 is 1