Question

Which of the following statements about magmatic gases is false?

1. mafic magmas tend to have higher gas contents than felsic magmas
2. when magmatic gases come into contact with water, the water typically becomes acidic
3. water vapor and carbon dioxide are typically the most abundant gases in magmas
4. magmas that have high gas contents are more likely to erupt explosively than magmas that have low gas contents
5. volcanic gas emissions have influenced Earth's climate over time

Answer 1

The false statement about magmatic gases is that mafic magmas have higher gas contents than felsic magma, which is not true as felsic magma typically contains more gases.

Step-by-step explanation:

The statement about magmatic gases that is false is the first one, which states that mafic magmas tend to have higher gas contents than felsic magmas. This is incorrect because felsic magmas generally contain more gas and are more viscous, owing to their higher silica content, which allows them to retain gas more efficiently compared to mafic magmas.

When magmatic gases come into contact with water, according to statement number 2, the water can indeed become acidic, particularly due to gases like sulfur dioxide. As for the most abundant gases in magma, water vapor, and carbon dioxide do typically dominate, which makes statement number 3 correct. Statement number 4 accurately reflects the relationship between gas content and explosive potential in magmas; higher gas content is often associated with more explosive eruptions. Lastly, statement number 5 is true, as volcanic gas emissions, which include greenhouse gases like carbon dioxide, have played a role in influencing Earth's climate over geological timescales.