Question

When light emitted by a white hot solid is passed through a sodium flame, the spectrum of the emergent light will show
(A) The $D_1$ and $D_2$ bright yellow lines of sodium
(B) Two dark lines in the yellow region
(C) All colours from violet to red
(D) No colours at all

Answer 1

Hint : A flame test is a chemical analytical process that uses each element's distinctive emission spectrum to determine the presence of particular elements, typically metal ions. Temperature affects the colour of flames in general; see flame colour. A spectrum is a situation that may fluctuate throughout a continuum without taking steps and is not confined to a certain set of values.

Complete Step By Step Answer:
A spectrum is a situation that may fluctuate throughout a continuum without taking steps and is not confined to a certain set of values. The term was initially used in optics to describe the rainbow of colours produced by visible light passing through a prism. As science learned more about light, it began to apply to the entire electromagnetic spectrum. As a result, it evolved into a mapping of a range of magnitudes (wavelengths) to a range of attributes, including the perceived "colours of the rainbow" and other features that correspond to wavelengths outside of the visible light spectrum. The bright doublet known as the Sodium D-lines at 588.9950 and 589.5924 nanometers dominates the sodium spectrum. These lines are released in a transition from the 3p to the 3s levels, as seen in the energy level diagram. The intensity of the line at 589.0 nm is double that of the line at 589.6 nm. When light from a white hot solid travels through sodium vapour, the energy from the white light spectrum is absorbed by the colder sodium vapour, resulting in a spectrum of intense yellow light with two black lines in the yellow area.
Hence option B is correct..

Note :
Sodium emits two wavelengths that are extremely near in wavelength and cannot be differentiated without specialised equipment. The wavelengths of these lines, dubbed the $D_1$ and $D_2$ Fraunhofer lines, are 589.6 nm and 589.0 nm, respectively. The lines were first seen as dark structures (absorption lines) in the Sun's optical spectrum. Fraunhofer lines were identified with letters ranging from A to K. The Sodium emission spectrum shows a significant doublet at 589.0 nm and 589.6 nm, indicating that the D-lines are caused by Sodium in the sun.