1772年，法国科学家____通过实验研究空气的成分；1869年，____发表了元素周期表。

阅读下面短文，在空白处填入一个适当的词，或填入括号中所给单词的正确形式。    I had my summer all planned out．I was going to enjoy the city． However, my parents had ____ different idea．They said l would be going to my grandparents' farm ____ a whole month．I felt sad．What could ____ (possible)be fun to do in the country?
    It was very hot when we arrived at the farm．So Grandpa took ____ (I)to a creek(小溪)．It felt great to jump into the cool，clear water．I ____ (begin)to think staying in the country might be ____ (interesting)than I had thought．
    The next day Grandma gave me a basket and sent me out ____(pick)strawberries．The berries were so good that a lot of them had disappeared ____ they reached my basket．
    I didn't get to visit a zoo， but l got an up-close look at pigs，cows，and ____ (chicken)．I fed the goats，milked the cows，and collected fresh eggs．
    My summer wasn't what I had expected，____ I loved it! I was sad that I had to leave．Now, I still love living in the city，but I learned that trying new things can be a lot of fun，too!

A、B两种固体物质的溶解度曲线如图所示．请回答：

（1）　 ____　℃时，A、B两种物质的溶解度相同；

（2）我国有些地区有一种说法：“冬天捞碱，夏天晒盐”．这里的碱指Na₂CO₃，盐是指NaCl．那么，图中　 ____　（填A或B）的溶解度曲线与Na₂CO₃的溶解度曲线相似；

（3）人们用上述方法从盐湖中捞得的Na₂CO₃（常含有少量的NaCl）．试计算Na₂CO₃的摩尔质量为　 ____　，2mol Na₂CO₃中约含有　 ____　个碳原子；

（4）某研究性学习小组对捞得的碱进行分析，称取Na₂CO₃固体（含有少量的NaCl）样品12.5g，将其配制成溶液，再向其中逐滴加入足量的稀盐酸，使气体完全放出，共收集到0.1molCO₂气体．该反应的化学方程式为　 ____，上述样品中含Na₂CO₃的物质的量为　 ____，质量为 ____

颜色变化常作为生物实验结果观察的一项重要指标。下面是学生在实验中遇到的问题，其中正确操作或想法是（  ）

张清莲是我国著名的化学家。1991年，他准确测得In的原子量为114.818，被国际原子量委员会采用为新的标准值。这是原子量表中的首次采用我国测定的原子量值。已知In的原子结构如图所示，则下列关于In的说法不正确的是