Which of the following bases will partially dissolve when placed in water? So partially dissolves means it partially dissociates or ionizes. So we're looking for the weak base out of all the options. If we were to take a look, remember strong bases are formed when certain group 1A and 2A metals combined with a basic anion.
If we take a look at the options, lithium, sodium, cesium and potassium, are those certain types of group 1A metals? So they could potentially make strong bases if they combine with the right basic anion. Aluminum. Aluminum on the other hand, is not one of those certain types of group 1A and 2A metals. In fact, it's not even found in Group 1A or 2A. It's a group 3A metal.
And because of that, it's not going to constitute a strong base. It's going to be a weak base. It's still a base since it's aluminum, a metal cation connected to hydroxide ion. A basic ion OK. Since it's weak, it'll only partially dissolve if we take a look at the other options. If we look, we have lithium here connected to hydroxide ion. This combination can make a strong base.
Here we have sodium ion connected to the amide ion. This also can make a strong base. Here we have cesium oxide. So cesium here which is plus one, is connected to the oxide ion. O2- this combination can make a strong base. And then finally we have potassium hydroxide. So potassium is K+ Hydroxide is OH-. So here this combination can make a strong base.
So out of all the options, only option C makes a weak base which only partially dissolve when placed in water.