【单选题】Speaker A:Could you give me a ride to the conference center? My presentation is in about half an hour.Speaker B;______Have you checked with Bob? He seems to be on his way there about this time.
【简答题】已知某试样可能含有 Na 3 PO 4 、 Na 2 HPO 4 、 NaH 2 PO 4 。今取试样 2.0000g ,以 0.5000mol/L HCl 溶液滴定至甲基橙终点,需用 32.00mL 。同样质量的试样,以 0.5000mol/L HCl 溶液滴定至酚酞终点,需用 12.00mL 。求试样中各组分的质量分数。 (Na 3 PO 4 、 Na 2 HPO 4 、 NaH 2 PO 4...