Question

The number of following statements which are incorrect line emission

• A. Line emission spectra used to study the electron structure
• B. The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet
• C. An absorption spectrum is like the photographic negative of an emission spectrum
• D. The element Helium was discovered in the sun by the spectroscopic method

Answer 1

The Correct Option is A

(A) Line emission spectra are used to study the electronic structure: This statement is correct. Line emission spectra are produced when electrons in an atom transition from higher energy levels to lower energy levels, emitting discrete lines of specific wavelengths. These lines correspond to specific energy differences between electron energy levels, providing valuable information about the electronic structure of the atom. 
(B) The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet: This statement is incorrect. The emission spectra of atoms in the gas phase do not show a continuous spread of wavelengths from red to violet. Instead, they exhibit distinct and discrete lines at specific wavelengths. These lines correspond to the emission of photons as electrons transition between energy levels. Each line corresponds to a unique energy difference, leading to the emission of light at specific wavelengths. 
(C) An absorption spectrum is like the photographic negative of an emission spectrum: This statement is correct. An absorption spectrum is indeed like the photographic negative of an emission spectrum. In an emission spectrum, you observe bright lines at specific wavelengths where electrons are transitioning down energy levels. In an absorption spectrum, you observe dark lines at the same wavelengths where specific frequencies of light are absorbed by the electrons as they move to higher energy levels. This is because the electrons absorb the energy needed to move to higher energy levels, leaving dark lines in the spectrum. 
(D) The element helium was discovered in the sun by the spectroscopic method: This statement is correct. The element helium was discovered spectroscopically. During a solar eclipse in 1868, astronomers observed a new yellow line in the solar spectrum, which did not correspond to any known element on Earth. This line was later identified as the spectral signature of helium. Helium was initially discovered in the spectrum of the sun before it was found on Earth. So, out of the given statements, only statement (B) is incorrect, as emission spectra do not show a continuous spread of wavelengths from red to violet.

The correct answer is option (A) : Line emission spectra used to study the electron structure