Question

Match the following metals with the colour of flame they produce:

• A. I – B; II – A; III – D; IV – C
• B. I – A; II – B; III – C; IV – D
• C. I – C; II – D; III – A; IV – B
• D. I – C; II – D; III – B; IV – A

Hint:

Flame colour is specific to metal ions due to electronic transitions, and can be used for qualitative identification.

Answer 1

The Correct Option is C

Step 1: Flame test principle.
The flame colour arises from the excitation of valence electrons in metal ions. When they return to the ground state, energy is released as visible light of characteristic wavelength (colour).

Step 2: Lithium (Li).
Li gives crimson red flame (B) due to electronic transitions in the Li\(^+\) ion.

Step 3: Potassium (K).
K gives a violet flame (D) because its emission lines lie in the violet region.

Step 4: Sodium (Na).
Na gives yellow flame (A) due to the strong Na D-line emission at 589 nm.

Step 5: Cesium (Cs).
Cs gives blue flame (C) due to its characteristic electronic transitions.

Step 6: Final conclusion.
Correct matching: Li – B, K – D, Na – A, Cs – C \[ \boxed{\text{Option (3)}} \]