【简答题】Text 4 As the twentieth century began, the importance of formal education in the United States increased. The frontier had mostly disappeared and by 1910 most Americans lived in towns and cities. Indu...
【单选题】标定 0.10 mol/LNaOH ,用草酸( H 2 C 2 O 4 90.04 ) 作基准物质, 精密称取 0.1636 g 的基准物质草酸,溶解后,以酚酞为指示剂,用 NaOH 滴定至终点,用去 26.06 mL 反应式为: H 2 C 2 O 4 +2 NaOH=Na 2 C 2 O 4 +2H 2 O 计算公式 计算 C NaOH 应是: