Match List - I with List - II. 

Choose the correct answer from the options given below :

• (A) Li (Lithium): Emits a characteristic crimson red color at 670.8 nm.
  $$\implies \text{(A)} \rightarrow \text{(III)}$$
• (B) Na (Sodium): Emits a classic intense yellow color at 589.2 nm.
  $$\implies \text{(B)} \rightarrow \text{(I)}$$
• (C) Rb (Rubidium): Emits a red-violet color at 780.0 nm.
  $$\implies \text{(C)} \rightarrow \text{(IV)}$$
• (D) Cs (Cesium): Emits a distinct blue color at 455.5 nm.
  $$\implies \text{(D)} \rightarrow \text{(II)}$$

Conclusion:

Matching the metals to their unique flame test atomic emission spectra lines gives the correct sequence.

Answer: Option D — (A)-(III), (B)-(I), (C)-(IV), (D)-(II)