The sodium D-line arises from the electronic trasnition _____ in Na atoms formed momentarily in the flame.

Options

A. `3s^(1)rarr4s^(1)`
B. `3s^(1)rarr3p^(1)`
C. `3s^(1)rarr4d^(1)`
D. `3s^(1)rarr4f^(1)`

Answer

B

Explanation

The color actually arises from electronic transitions in short-lived species which are formed momentarily in the flame. The flame is rich in electrons, In case of Na, the ions are temporaily reduced to atoms:
`Na^(+)+e^(-)rarrNa`
The sodium D-line (which is actually a doublet at 589.0mn and 589.5nm) arises from the electronic transition `3s^(1)rarr3p^(1)` in Na atoms formed in the flame.
The colors from different elements do not arise at all from the same transition or from the same species, For example, the red line for Li arises from a short-lived LiOH species formed in the flame.