Chemistry help. (10 points)?

There's two types of displacement. One where two compounds switch one of the elements which is double displacement. This case however is single displacement because the compounds are trading but rather the element that is alone is trading places with the element already in the compound. Therefore, it's single displacement. Also it's hard to predict the physical appearance of a compound, but you can try google imaging it or something. As for why it's a hydroxide and not just oxygen, you need to do a bit of memorization. Whenever a metal reacts with water, the result is a hydroxide. You just have to remember that. Good luck!