1) What is a substance made of only one kind of atom? a) mixture b) compound c) element d) solutions 2) Which of the following is a compound? a) Oxygen (O₂) b) Water (H₂O) c) Gold (Au) d) Iron (Fe)

Science 2013

由
打印
嵌入

排行榜

视觉风格

选项

切换模板

恢复自动保存：？