题干

润东、宇豪、舜楠三位同学在实验室进行有关酸的化学性质实验。他将稀盐酸加入氢氧化钠溶液中,没有观察到明显现象。通过查阅书本确认盐酸和氢氧化钠会反应生成水和氯化钠。他们现在想探究这个实验中,盐酸和氢氧化钠是否恰好完全反应。

[提出猜想]猜想一:反应后的溶液溶质只有氯化钠;

猜想二:反应后的溶液溶质有氯化钠和____;

猜想三:反应后的溶液溶质有氯化钠和____;

已知氯化钠溶液呈中性。

提供的仪器和试剂有:试管、滴管、药匙、酚酞试液、锌粒、氧化铁粉末、大理石

步骤

操作

现象和结论

Ⅰ

取少量反应后的液体样品于试管中。

____

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同类题4

阅读理解

    Some years ago, writing in my diary used to be a usual activity. I would return from school and spend the expected half hour recording the day's event, feelings, and impressions in my little blue diary. I did not really need to express my emotions by way of words, but I gained a certain satisfaction from seeing my experiences forever recorded on paper. After all, isn't accumulating memories a way of preserving the past?

    When I was thirteen years old, I went on a long journey on foot in a great valley, well-equipped with pens, a diary, and a camera. During the trip, I was busy recording every incident, name and place I came across. I felt proud to be spending my time productively, dutifully preserving for future generations a detailed description of my travels. On my last night there, I wandered out of my tent, diary in hand. The sky was clear and lit by the glare of the moon, and the walls of the valley looked threatening behind their screen of shadows. I automatically took out my pen….

    At that point, I understood that nothing I wrote could ever match or replace the few seconds I allowed myself to experience the dramatic beauty of the valley. All I remembered of the previous few days were the dull characterizations I had set down in my diary.

    Now, I only write in my diary when I need to write down a special thought or feeling. I still love to record ideas and quotations that strike me in books, or observations that are particularly meaningful. I take pictures, but not very often—only of objects I find really beautiful. I'm no longer blindly satisfied with having something to remember when I grow old. I realize that life will simply pass me by if I stay behind the camera, busy preserving the present so as to live it in the future.

    I don't want to wake up one day and have nothing but a pile of pictures and notes. Maybe I won't have as many exact representations of people and places; maybe I'll forget certain facts, but at least the experiences will always remain inside me. I don't live to make memories—I just live, and the memories form. themselves.