题干

下列各组微粒能大量共存,当加入相应试剂后会发生化学变化,且发生反应的离子方程式书写正确的是(  )

选项

微粒组

所加试剂

离子方程式

A

NH4+、Mg2+、SO42﹣

少量Ba(OH)2溶液

NH4++SO42﹣+Ba2++OH﹣=BaSO4↓+NH3•H2O

B

Mg2+、HCO3﹣、Cl﹣

过量NaOH溶液

 Mg2++2HCO3﹣+2OH﹣=MgCO3﹣↓+CO32﹣+2H2O

C

H+、Na+、NO3﹣

Fe粉

Fe+2H+=Fe2++H2↑

D

Ca2+、NH3•H2O、Cl﹣

通入过量CO2

NH3•H2O+CO2=NH4++HCO3﹣

A:A

B:B

C:C

D:D

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答案(点此获取答案解析)

D

同类题4

阅读下面短文, 从短文后各题所给的四个选项(A、B、C、D)中, 选出可以填入空白处的最佳选项。

    William Franklin came to my class half a year ago.But from his first day here,he 1 himself in his own world and he never spoke to others.As his teacher,I tried to start a talk with him but 2.It seemed as if he just didn't want to break his 3.

    After the Thanksgiving holiday,we received the news of the4Christmas collection of money for the 5 in our school."Christmas is a season of 6,"I told my students."Some poor students in our school might not have a 7 holiday.By giving a little money,you will help 8 some toys,food and clothing for these needy students.We will 9 the collection tomorrow." 

    The next morning, 10 ,I found out almost everyone had 11 this matter except Willard Franklin.He came up to my desk with his head down. 12 ,he dropped two coins into the small box."I don't need milk for lunch,"he said in a 13 voice.

    After school I couldn't help sharing what had 14 in the morning with our headmaster."I may be wrong,but I 15 Willard might be ready to become part of our class. "I am 16 to hear that," he nodded."And I just received a list of the poor families in our school who most need 17 .Here,take a look at it."

    As I sat down to 18 ,I found Willard Franklin was at the top of the list.At that moment,I felt I really 19 Willard for the first time:a cold face with a warm heart.From this 20 ,I also learnt that whether rich or poor,every child has a kind heart.