Read and answer the following questions. Encircle the letter of the best answer. 1. During a volcanic eruption, magma is ejected out of the volcano. Which of the following BEST describes a magma? A. Magma are gases given off by active volcanoes. B. Magma is a molten rock that breaks through the Earth's surface. C. Magma is rock fragments and particles ejected by a volcanic eruption. D. Magma is an extremely hot liquid and semi-liquid rock located under the Earth's surface. 2. Magmas vary widely in their chemical composition. Which of the following is the most abundant element in magma? A. Aluminum B. Magnesium C. Oxygen D. Silicon 3. Viscosity is the property of the material's resistance to flow. It is also described as the liquid's thickness and stickiness. Which of the following factors greatly affects the viscosity of magma? A. pressure, silica content, tephra emission, and altitude B. temperature, silica content, and amount of dissolved gases C. temperature, surface currents, pressure, and silica content D. temperature, pressure, altitude, and amount of dissolved gases 4. The temperature of magma greatly affects its viscosity. How will you describe the relationship between temperature and viscosity? A. The lower the temperature of magma is, the lower is its viscosity. B. The higher the temperature of magma is, the lower is its viscosity. C. The higher the temperature of magma is, the higher is its viscosity. D. The temperature and viscosity of magma are not related to each other. 5. Silica content mainly affects the explosiveness of a volcanic eruption. Which of the following statements describes the negative effect of volcanic eruption? A. A volcanic eruption can cause loss of lives and properties. B. People became creative by making earthenware out of the ashfall from the volcanic eruption. C. The lava and ash from the eruption break down to provide valuable nutrients for the soil. D. The strong winds during volcanic eruption spread the aerosol particles from the plume around the globe and result in the measurable cooling of the Earth's surface.
