【单选题】在pH=10.0的氨性缓冲溶液中用EDTA滴定Zn 2+ 至50%处时 ( )
【单选题】在 pH 为 10.0 的氨性缓冲溶液中,用 EDTA 滴定 Zn 2+ 至 50 %时
D.
pZn 与 [NH 3 ] 和 c ( Zn )均有关
【简答题】在pH=10.0的氨性缓冲溶液中,以0.02000mol/L EDTA标准溶液滴定0.02000mol/L Mg2+或Ca2+溶液,以EBT为指示剂,计算终点误差。KCaY>KMaY,为什么滴定Ca2+比滴定Mg2+的终点误差反而要大?(lgKCaY=10.69,lgKCa—EBT=5.4 lgKMgy=8.69 lgKMg—EBI=7.0)
【简答题】Seldom___my boss in such a good mood since I came to work in this company.
【单选题】对味觉的叙述,错误的是 ( )
B.
人舌表面的各个部位对不同味刺激的敏感度差不多
【单选题】My mother seldom allow me ______ with my friends on weekends.
【单选题】在 pH 为 10.0 的氨性缓冲溶液中,用 EDTA 滴定 Zn 2+ 至 150 %时
D.
pZn′ 与 lgK′(ZnY) 、 c(Y) 均有关
【单选题】26 I have seldom seen my mother——pleased with my progress as she is now
【单选题】In Para. 3, it is implied that ______.
A.
my grandfather seldom talked his history with his family
B.
my grandfather took part in the World War Two
C.
my father knew more about history
D.
my grandfather talked with us face-to-face