题目

下列操作达不到预期目的是（ ） ①石油分馏时把温度计插入液面以下 ②用溴水除去乙烯中混有的SO2气体 ③用乙醇与1mol/L的H2SO4混合共热到170℃制取乙烯 ④将饱和食盐水滴入盛有电石的烧瓶中制乙炔． A．①④B．③④C．②③④D．①②③ 答案：【考点】化学实验方案的评价；乙烯的实验室制法；乙炔炔烃；物质的分离、提纯和除杂；石油的分馏． 【分析】①石油分馏时温度计测量蒸气温度； ②二氧化硫和乙烯都和溴发生反应； ③用乙醇与浓H2SO4混合共热到170℃制取乙烯； ④电石和水反应生成氢氧化钙和乙炔． 【解答】解：①石油分馏时温 Hi! I'm Kate．I'm from America．Now I am   1   Beijing．I am   2   English teacher．I teach English   3  ．I like sports．I have a happy family．I have   4   children．They are Jack and Grace．Jack is nine   5   his sister Grace   6  only（仅仅）three．Jack is  7  school．But Grace   8 ．She is in Yang Guang kindergarten．Jack has a great stamp（邮票）collection．But Grace doesn't have   9  ．But she   10   some postcards（明信片）．She thinks they are beautiful．I love my children． 1．A．in                         B．on                          C．at 2．A．a                         B．an                         C．the 3．A．well                       B．nice                        C．good 4．A．three                      B．two                           C．four 5．A．and                           B．so                          C．or 6．A．are                           B．is                          C．has 7．A．at                         B．to                       C．for 8．A．doesn't                            B．isn't                      C．don't 9．A．one                           B．those                      C．these 10．A．have                       B．has                        C．there is