22. For phosphoric acid, Ka,1 = 7.6 × 10⁻³, Ka,2 = 6.2 × 10⁻⁸, Ka,3 = 4.8 × 10⁻¹³. In order of decreasing concentrations, which of the following is correct about the concentration of the listed species present in a solution of H3PO4 at pH = 8? I. [PO4³⁻] II. [HPO4²⁻] III. [H2PO4⁻] IV. [H3PO4] (A) I ＞ II ＞ III ＞ IV (B) I ＞ III ＞ IV ＞ II (C) III ＞ II ＞ IV ＞ I (D) IV ＞ I ＞ III ＞ II (E) IV ＞ III ＞ II ＞ I

22. For phosphoric acid, Ka,1 = 7.6 × 10⁻³, Ka,2 = 6.2 × 10⁻⁸, Ka,3 = 4.8 × 10⁻¹³. In order of decreasing concentrations, which of the following is correct about the concentration of the listed species present in a solution of H3PO4 at pH = 8?

I. [PO4³⁻] II. [HPO4²⁻] III. [H2PO4⁻] IV. [H3PO4]

(A) I ＞ II ＞ III ＞ IV
(B) I ＞ III ＞ IV ＞ II
(C) III ＞ II ＞ IV ＞ I
(D) IV ＞ I ＞ III ＞ II
(E) IV ＞ III ＞ II ＞ I

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統計： A(0), B(0), C(2), D(0), E(1) #3252564

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B1 · 2025/10/21

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題目解析題目中給定了磷酸（H₃PO₄...

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4. A strip of copper is placed in a 1 M solution of copper nitrate, and a strip of silver is placed in a 1 M solution of silver nitrate. The two metal strips are connected to a voltmeter by wires, and a salt bridge connects the solutions. The following standard reduction potentials apply: Ag+(aq) + e- → Ag(s) E° = +0.80 V Cu2+(aq) + 2e- → Cu(s) E° = +0.34 V When the voltmeter is removed and the two electrodes are connected by a wire, which of the following does .not. take place? (A) Negative ions pass through the salt bridge from the silver half-cell to the copper half-cell. (B) Some positive copper ions pass through the salt bridge from the copper half-cell to the silver half-cell. (C) The silver electrode increases in mass as the cell operates. (D) Electrons flow in the external circuit from the copper electrode to the silver electrode. (E) There is a net general movement of silver ions through the salt bridge to the copper half-cell.

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