A train stops at a station(车站). A young man wants to come out, but it is raining. A boy is standing under a big umbrella. The young man says to the boy，"Can you go and get us two hamburgers, one for you and one for me? Here are two dollars. " "Great！"says the boy and he goes to buy hamburgers. After some time, the boy is back. He is eating a hamburger. "Where is my hamburger？"asks the young man. "Oh, there is only one hamburger left(剩下). So I'm eating mine. Here is your dollar. "

在一幅地图上量得甲、乙两地相距2厘米，两地实际距离100千米，这幅地图的比例尺是（　　）

⑴将此固体粉末加到水中，得到白色沉淀和上层无色清液；

⑵过滤后，在滤出的白色沉淀里加入稀硝酸，白色沉淀部分溶解并有无色气体生成，该气体使澄清石灰水变浑浊；

⑶在滤液中，加入适量的氢氧化钠溶液并加热，生成有刺激性气味的无色气体，该气体能使湿润的红色石蕊试纸变蓝．

由此实验推断：该粉末中一定含有：____、____、____、____；一定不含有____；可能含____．（填化学式）写出步骤（2）中方程式：____；____．