Molten Lava, The Deepest Mystery of Our Planet!

What is the name for a natural opening in the Earth's crust through which molten rock, ash, and gases erupt?
What is the name for the area of land where all of the water that falls in it and drains off of it goes into the same place?
What is the name for the study of the relationship between humans and their environment?
What is the name of the highest mountain in Africa?
Which country was ruled by the tsars?
Which empire was ruled by Julius Caesar?
Which event is considered the start of the Protestant Reformation?