【查阅资料】氮化镁(Mg3N2)是一种淡黄色固体,能和水反应,生成Mg(OH)2和NH3;
NH3能使湿润红色石蕊试纸变蓝色.
【实验步骤】
①将足量白磷在空气中点燃后,迅速伸入钟罩内,塞紧橡皮塞(图1);
②待钟罩内水面不再变化时,向水槽中加水,使水槽中液面与钟罩内液面相平;
③打开橡皮塞,将燃着的螺旋状镁条迅速伸入钟罩内,塞紧橡皮塞(图2);
④待钟罩内水面不再变化时,观察钟罩内壁及表面皿中固体颜色,取少量固体加入水中.
【分析】
用固体样品配制一定物质的量浓度的溶液,需经过溶解、转移、定容、摇匀等操作.下列图示对应的操作不规范的是( )
完型填空 When I was walking down the street the other day, I happened to1a small brown purse2 on the road. I3it up and opened it to see if I could4 the owner's name. There was5 inside it6 some changes (零钱) and an old photo--a picture of a woman and a young girl of about twelve years old who looked7 the woman's daughter. I put the photo back and8 the purse to police station, 9 I handed it to an officer. Before I left, the officer took my name and address10the owner might want to write and thank me.