一定量的铜和浓硫酸在加热条件下充分反应，向反应后的溶液中逐滴

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问题选择题

一定量的铜和浓硫酸在加热条件下充分反应，向反应后的溶液中逐滴加入含a mol NaOH的溶液，恰好使反应后的溶液呈中性，则下列叙述错误的是(　　)

A．溶液中c(Na^＋)＝2c(SO₄^2-)

B．mol＞沉淀的物质的量＞0

C．沉淀的物质的量＝mol

D．原浓硫酸中H₂SO₄的物质的量＞mol

答案

答案：C

铜和浓硫酸反应后的溶液中含有CuSO₄和H₂SO₄，加入含a mol NaOH的溶液后显中性，此时溶液中的溶质为Na₂SO₄，Cu²^＋完全沉淀，A项正确；n(CuSO₄)＜ mol，故B项正确，C项错；由于有一部分浓硫酸被还原为SO₂，故n(H₂SO₄)＞ mol，D项正确。

完形填空

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4  while they are watching and listening. When they are getting older, they begin to   5  story books, science books..., anything they like. When they find something new, they love to ask questions and   6  to find out the answer.
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填空题

水是生命之源，我们应该节约水、爱护水资源。

(1)水是由__________两种元素组成。

(2)日常生活中通过__________可以降低水的硬度。

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