According to the author, the number of orphans in Malawi could reach as high as ______.
A. 475,000
B. 100,000
C. 1,000,000
D. 5,000
查看答案
Andrew Kayinga, 15, handicapped,________.
A. is spported by his relatives
B. thinks that he has a bright future before him
C. wants to get employment in a school
D. is not realistic about his future
浓度相同的下列阴离子的水溶液，碱度最强的是
Ac-(Ka＝1.8×10-5)
B. CN-(Ka＝6.2×10-10)
CO32-(Ka1＝4.2×10-7; Ka2＝5.6×10-11)
D. F-(Ka＝3.5×10-4)
浓度为c(HCl)(mol/L)的HCl和c(NaOH)(mol/L)的NaOH混合溶液的质子平衡方程是
A. [H+] = [OH-]+c(HCl)
B. [H+]+c(NaOH) = [OH-]+c(HCl)
C. [H+]+c(NaOH) =[OH-]
D. [H+] = [OH-]+c(HCl)+c(NaOH)
已知H2C2O4的pKa1 = 1.22, pKa2 =4.19。今有一草酸溶液的pH = 3.66, 则其主要存在形式是
A. H2C2O4
B. HC2O4-
C2O42-
D. H2C2O4 + HC2O4-
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