1. (2024六下·江源期末) 将下列实验与实验现象相连接。

 蜡烛燃烧                                                                                   产生气体

 硫酸铜溶液和氢氧化钠溶液混合                                                  产生沉淀

 小苏打与白醋反应                                                                     发光发热

 铁钉生锈                                                                                   颜色改变