A:BaSO4的水溶液导电性极弱:BaSO4⇌Ba2++SO42﹣
B:KHSO4在熔融状态下可导电:KHSO4=K++H++SO42+
C:常温下,0.1 mol/L的HF 溶液的pH>1:HF+H2O⇌H3O++F﹣
D:向KI﹣淀粉溶液中滴加稀硫酸,溶液变蓝色:4I﹣+O2+2H2O=2I2+4OH﹣
等边三角形的内切圆半径,外接圆半径和高的比是( )
⑴____ A.music B. can C. pencil D. cousin
⑵____ A. always B. some C. sister D. subject
⑶____ A. mine B. tidy C. nine D. habit
⑷____ A. thank B. happy C. want D. jacket
⑸____ A. dear B. pear C. near D. hear
如图所示,长为L的细绳一端固定,另一端系一质量为m的小球.给小球一个合适的初速度,小球便可在水平面内做匀速圆周运动,这样就构成了个圆锥摆,设细绳与竖直方向的夹角为θ.下列说法中正确的是( )