Which one of the following statements is not true?

a. Basalt magmas, in general, have higher temperatures than rhyolite magmas.

b. When magma reaches the surface, its dissolved gas content increases.

c. Melting temperatures of silicate rocks are lowered by small amounts of water.

d. Melting temperatures of silicate rocks increase with increased pressure.

Question

Chemistry

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5 May, 22:10

Which one of the following statements is not true?

a. Basalt magmas, in general, have higher temperatures than rhyolite magmas.

b. When magma reaches the surface, its dissolved gas content increases.

c. Melting temperatures of silicate rocks are lowered by small amounts of water.

d. Melting temperatures of silicate rocks increase with increased pressure.

+3

Answers (1)

Know the Answer?

Joslyn Nguyen · Answer 1

When magma reaches the surface, its dissolved gas content increases is true

Explanation:

The volcanic eruptions happen because of magma that is expelled on the earth's surface. At the earth's depth, all magma have gas dissolved in liquid. When the pressure has decreased the magma rises towards the earth's surface creating a separate vapour phase.

As pressure reduces the volume of gas will expands and giving magma its 'explosive character'. Thus, as magma reaches the surface the dissolved gas content decreases and magma comes out of earth's surface.