①甲的密度;
②酒精对容器底的压强;
③若再向两容器中分别倒入体积相同的酒精和水,是否有可能使液体对容器底的压强相同.若有可能请求出体积值,若不可能请通过计算说明.
则ρ甲= m甲<
如图,将图案绕点O按逆时针方向旋转90°,得到的图案是( )
向含Fe2+、I﹣、Br﹣的溶液中通入过量的氯气,溶液中四种粒子的物质的量变化如图所示,已知b﹣a=5,线段Ⅳ表示一种含氧酸,且Ⅰ和Ⅳ表示的物质中含有相同的元素.下列说法正确的是( )
若集合A={x|x2-9x<0,x∈N*},B={y|4y∈N*},则A∩B中元素个数为 ( )
读短文,回答问题。
May: Good morning! Can I help you?
Lucy: Yes. I want some pencils and pens.
May: We have many here. Which one do you like?
Lucy: That red one, please.
May: Here you are.
Lucy: Thank you. How much is it?
May: It's cheap. It's 1 yuan.