Question 1

How does magma usually form in mid-ocean ridges?

Accepted Answer

Decompression melting

Answer

Flux melting

Answer

Compression melting

Answer

Heat transfer

Question 2

Which of the following describes flux melting?

Accepted Answer

Adding water and carbon dioxide to mantle rocks make them melt easier.

Answer

Rocks melt more easily because of increase in temperature.

Answer

Heat is transferred to surrounding rocks causing them to melt.

Answer

Rocks melt more easily because of decrease in pressure.

Question 3

The figure below shows decompression melting at divergent plate boundaries. Which of the following describes decompression melting?

Accepted Answer

Decrease in pressure at high temperature causes rocks to melt.

Answer

Rising hot water reacts with rock causing them to melt.

Answer

Increase in pressure at high temperature causes rocks to melt.

Answer

Hotter rocks transfer heat to cooler surrounding rocks.

Question 4

Which of the following is TRUE about magma?

I. It contains a liquid base.

II. It can be found in Earth’s core.

III. It has minerals, rocks, and dissolved gases.

IV. It can be found in the lower part of the crust and uppermantle.

Accepted Answer

I, III and IV

Answer

I, II and III

Answer

Answer

Question 5

The figure below shows an oceanic plate and a continental plate in a

convergent plate boundary. How does magma form in this type of plate boundary?

Accepted Answer

Adding water or carbon dioxide lowers the rocks' melting point.

Answer

Water in the subducting sea floor would lower the melting temperature of the mantle.

Answer

Hot rocks from the mantle rise to an area of lower pressure.

Answer

Hotter rocks from the plate below rise into the cooler plate above, transferring heat.

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