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5.常溫下,在下列溶液中一定能大量共存的離子組是

   A.由水電離產(chǎn)生的C(H+)=l×10-10mol·L-1:Na+、Ba2+

   B.含有大量Fe3+的溶液:Na+、NH4+、、

   C.含有大量的溶液:、Fe2+、H+

    D.能與Al反應(yīng)產(chǎn)生H2的溶液:、、Mg2+、K+

試題詳情

4.如圖,電解用粗鹽(含Mg2+、Ca2+、等雜質(zhì))配制的食鹽水,以下說法正確

  的是

     A.a(chǎn)是電解池的陰極    

    B.a(chǎn)電極上發(fā)生還原反應(yīng)

     C.b電極附近有白色沉淀出現(xiàn)  

    D.b電極上有黃綠色氣體產(chǎn)生

試題詳情

3.電解稀H2SO4、Cu(NO3)2、NaCl的混合液,最初一段時(shí)間陰極和陽極上析出的物質(zhì)分別是

   A.Cu和C12   B.H2和C12    C.H2和O2     D.Cu和O2

試題詳情

2.對(duì)于化學(xué)反應(yīng)方向的確定,下列說法正確的是

     A.溫度、壓力一定時(shí),放熱的、熵減小的反應(yīng)一定能自發(fā)進(jìn)行

     B.溫度、壓力一定時(shí),焓因素和熵因素共同決定一個(gè)化學(xué)反應(yīng)的方向

     C.反應(yīng)焓變是決定反應(yīng)能否進(jìn)行的唯一因素

     D.固體的溶解過程與熵變無關(guān)

試題詳情

1.下列關(guān)于能量轉(zhuǎn)換的認(rèn)識(shí)中不正確的是

     A.電解水生成氫氣和氧氣時(shí),電能轉(zhuǎn)化成化學(xué)能

     B.煤燃燒時(shí)化學(xué)能主要轉(zhuǎn)變成熱能

     C.綠色植物光合作用過程中光能轉(zhuǎn)變成化學(xué)能

     D.白熾燈工作時(shí)電能轉(zhuǎn)變化學(xué)能

試題詳情

15、    I explained on the phone,your request will be considered at the next meeting.

A、When     B、After      C、As          D、Since

1-----5CDDBB    6----10DAAAC     11-----15CDACC

試題詳情

14、I walked in our garden,    Tom and Jim were tying a big sign onto one of the trees.

A、which     B、when      C、where        D、that

試題詳情

13、Great changes have taken place in that school.It is no longer    it was 20 years ago,    it was so poorly equipped.

A、what;when   B、that;which    C、what;which      D、which;that

試題詳情

12、You must keep on working in the evening,    you are sure you can finish the task in time.

A、as     B、if     C、when    D、unless

試題詳情

11、Hardly had the game begun   it started to rain.

A、as     B、than    C、when    D、while

試題詳情


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