Flame test and H2SO4 reaction identify ions in the compound

Steps:

• X is the metal cation; red flame test identifies Sr^{2+} (strontium), while Ba^{2+} gives green.
• Y is the anion; reaction with concentrated H2SO4 producing H2S occurs with I^-, as HI reduces H2SO4 to H2S, I2, and SO2.
• Br^- with concentrated H2SO4 yields Br2 and SO2, but no H2S.
• Compound containing Sr^{2+} and I^- is SrI2.

Why D is correct:

• Sr^{2+} produces crimson red flame; I^- reacts with concentrated H2SO4 via 8HI + 5H2SO4 → 4I2 + H2S + 4SO2 + 4H2O.

Why the others are wrong:

• A: Ba^{2+} gives apple-green flame, not red.
• B: Ba^{2+} gives apple-green flame, not red.
• C: Br^- produces Br2 and SO2 with concentrated H2SO4, not H2S.

Final answer: D