Which statement best describes the species XO_2^- that is dissociated from HXO_2 in aqueous solution?

• A. XO_2^- is a radical species formed by the loss of an electron from HXO_2.
• B. XO_2^- is a cation formed by the gain of a proton by HXO_2.
• C. XO_2^- is a neutral molecule that does not carry any charge.
• D. XO_2^- is an anion formed when HXO_2 loses a proton (H^+) in water.

Answer: (D)

Verified step by step guidance

1. Identify the species involved: HXO_2 is an acid that can dissociate in water, and XO_2^- is the species formed after dissociation.
2. Recall that acids dissociate by losing a proton (H^+), so when HXO_2 dissociates, it loses H^+ and forms its conjugate base.
3. Understand that losing a proton (H^+) means the species gains a negative charge, making XO_2^- an anion, not a neutral molecule or a cation.
4. Recognize that XO_2^- is not a radical because radicals have unpaired electrons, and this species is formed by proton loss, not electron loss.
5. Conclude that the best description is that XO_2^- is an anion formed when HXO_2 loses a proton (H^+) in aqueous solution.