Answer: Option [B]This is the scale used to measure the size of volcanic eruptions Volcanic Explosivity Index. The Volcanic Explosivity Index (VEI) is a scale that describes the size of explosive volcanic eruptions based on magnitude and intensity.
Answer: Option [D]Eruptions from composite volcanoes are usually loud and more violent. Composite cone volcanoes have the most violent eruptions because the magma being erupted is very viscous. This means it doesn't flow easily. More viscous magma has high silica content.
Answer: Option [B]Acid lava flows slowly as it is highly viscous. Acid lava is highly vicious in nature, with high melting point, it is light in colour, it is high in silica content, it is slow moving and it comes from cone volcanoes whereas basic lava is non-vicious in nature, it is mafic, it flows faster and is high in potassium.
Answer: Option [D]Passageway which joins vent to crater of volcano is known as Pipe.
Answer: Option [C]Eruptions of composite volcanoes are loud and violent because that contain viscous acid lava.