【单选题】China's first Mars probe,Yinghuo-1,is expected to be launched in the second half of this year and it will be the first time that China will __________ another planet. [ ]
【简答题】听对话,回答问题。 1. When did the girl come back home? A. On Saturday. B. On Friday. C. On Wednesday. 2. What's the dialogue mainly about? A. The girl's vacation. B. The girl's parents. C. The girl's interest...
【简答题】今有0.10mol·L -1 甲酸与等浓度的氯化铵的混合液。选择哪种指示剂?(HCOOH的K a =1.8×10 -4 ,NH 3 的K b =1.8×10 -5 )
【单选题】10mol/L NH 2 OH 和 0.20mol/L NH 4 + 混合溶液的pH为( ) 已知羟胺 NH 2 OH K b = 9.1 × 10 -9 , NH 3 的 K b = 1.8 × 10 -5
【单选题】NH 3 的 K b =1.8×10 -5 ,0.1mol/L NH 3 溶液的 pH 为( )。
【单选题】已知NH 3 的K b =1.8×10 -5 ;则NH 4 + 的Ka是: ( )
【单选题】As a little boy, there was nothing I liked better than Sunday afternoons on my grandfather’s farm. 1 by miles of winding stonewalls, the house and barn provided endless hours of 2 for a city kid like ...