—________ is ten plus twenty?
—It's thirty. [ ]
A. How much
B. How many
C. What
D. How
答案:C
已知下列两个反应,前者较后者更易发生(1)NH3+H+⇌NH+4(2)Ag++2NH3⇌[Ag(NH3)2]+欲使银氨溶液中转化出大量的Ag+,适宜的试剂是( )
A.NaOH
B.HCl
C.HNO3
D.NaHSO4
消费结构就是指恩格尔系数。[ ]