问题
选择题
With tags (标签) _____ to the luggage, it won't take long for the passengers to find theirs correctly. |
A. attaching B. attached C. to attach D. attaches |
答案
答案:B
With tags (标签) _____ to the luggage, it won't take long for the passengers to find theirs correctly. |
A. attaching B. attached C. to attach D. attaches |
答案:B
根据已有内容的规律进行增补
(1)同族元素单质间的置换反应的化学方程式:
①2Na+2H2O=2NaOH+H2↑ ②2HBr+Cl2=2HCl+Br2 ③2H2S+O2=2S+2H2O ④______
(2)已知
化学键 | Si-O | Si-Cl | H-Cl | Si-Si |
键能/KJ•mol-1 | 460 | 360 | 431 | 176 |
①比较熔点SiCl4______SiO2(填“>”或“<”),
②工业制纯硅反应:
SiCl4(g)+H2(g)=1 2
Si(s)+2HCl(g)△H=+118KJ•mol-1则H-H键能为______KJ•mol-1.1 2