What is the term for molten rock that has been ejected from a volcano?

Which of the following is a characteristic of a shield volcano? Which volcano is located in the Andes mountain range and is the highest active volcano in the world? What is the name of the volcano that destroyed the city of Pompeii in 79 AD? What is the term for the scientific study of volcanoes? What is the name of the largest volcano in the solar system? Which of the following is a common gas emitted by volcanoes? What is the name of the famous volcano that erupted in 1815 and caused the 'Year Without a Summer'? Which type of eruption is characterized by a gentle, non-explosive release of lava?