Third Quarter Periodic Test — Science 9 (SY 2025–2026)

Which of the following best explains the difference between a mountain and a volcano?

• Mountains are formed in the mantle plume, while volcanoes are formed in the lithosphere.

• Both mountains and volcanoes are created by the same process, but volcanoes are smaller in size.

• Mountains are formed by volcanic eruptions, while volcanoes are formed by the movement of tectonic plates.

• Mountains are formed by the uplift of the Earth’s crust, while volcanoes are formed by the eruption of magma from beneath the Earth’s surface.

Volcanoes have unique parts that make them different from mountains. Which of the following parts are found only in volcanoes?

I. Base II. Crater III. Lava IV. Summit

• I only

• II only

• II and III

• III and IV

Volcanoes vary in structure and size. Which of the following is TRUE about cinder cone volcanoes?

• They are large and have gentle slopes.

• They form from the collapse of large magma chambers.

• They are formed primarily by quiet and non-explosive eruptions of low-viscosity lava.

• They are made up of accumulated pyroclastic materials like volcanic ash and volcanic bombs.

The Philippines has several active and inactive volcanoes; the following are correctly matched EXCEPT?

• Cabaluyan – inactive

• Isarog – inactive

• Mayon – active

• Smith – active

Given the following examples, which are active volcanoes? I. Arayat in Pampanga II. Kanlaon in Negros Oriental III. Mayon in Albay IV. Taal in Batangas

• I and II only

• II and III only

• I, II, and III only

• II, III, and IV only

The Taal volcano in Batangas had a minor phreatic or hydrothermal eruption last November 28, 2024. Which of the following statements BEST describes a phreatic eruption?

• It is a highly explosive type of gas and pyroclastic eruption.

• It happens when magma heats the groundwater, causing a steam-blast eruption.

• It is a weak to violent eruption that occurs regularly and is characterized by lava fountains.

• It is a powerful volcanic eruption that produces a massive column of ash and gas that extends high into the atmosphere.

Refer to the image below. Magma forms when solid rock in the Earth’s mantle or crust melts. Which is TRUE about the formation of the magma?

• Hot molten rocks are found in the upper portion of the lithosphere.

• The presence of carbon dioxide and water does not affect magma formation.

• Partial melting of the rocks happens when the oceanic crust sinks, and the volatiles decrease the melting point of the rocks.

• Decompression melting happens in the subduction zone, where the pressure is reduced, and the temperature remains constant.

How does temperature affect the movement of particles in magma and its viscosity?

• Temperature does not affect the movement of particles in magma.

• Higher temperature causes magma to become solid and increase viscosity.

• Higher temperature causes particles to move more rapidly, reducing magma viscosity.

• Higher temperature causes particles to move more slowly, making magma more viscous.

Mt. Pinatubo erupted violently last June 15, 1991, extruding large amounts of pyroclastic materials that reached more than 20 km in height. How does the viscosity of Mt. Pinatubo’s magma influence the explosiveness of its eruption?

• Less viscous magma traps gases, leading to a non-explosive eruption.

• Less viscous magma leads to a more explosive eruption, as gases cannot escape.

• More viscous magma allows gases to escape easily, leading to a non-explosive eruption.

• More viscous magma traps gases, increasing the pressure and leading to a more explosive eruption.

Kilauea is one of the world’s most active volcanoes. It has effusive eruptions, which are not violent and pour out lava. How does the silica content of Kilauea’s magma affect the type of its eruption?

• Magma with low silica content (basaltic) tends to produce effusive eruptions.

• Magma with low silica content (basaltic) tends to produce explosive eruptions.

• Magma with high silica content (rhyolitic) produces eruptions without gas release.

• Magma with high silica content (rhyolitic) tends to produce non-explosive eruptions.