题目9单选题
在氨性缓冲溶液中,用EDTA标准溶液滴定Zn2+.滴定到达化学计量点时,下述关系式成立的是A. <img src="https://tihai-oss-cloud.itihey.com/img/01bb1c57f676a45f9f8efbf3c94dfcc8.png">B. <img src="https://tihai-oss-cloud.itihey.com/img/faf362ef818024fbc6ff17a262bc6dd0.png">C. <img src="https://tihai-oss-cloud.itihey.com/img/6f24b40991467f9ae1fd35e37b865fd9.png">D. <img src="https://tihai-oss-cloud.itihey.com/img/ff1d4df0c4921d443eaff0aa7986ad6a.png">