Question

composition of earth and moon
percent by mass (%)
60
40
20
0
47 43
27 20
2 19
5 10
4 3
8 3
7 2
oxygen
silicon
magnesium
iron
calcium
aluminum
other elements
element
earths crust moons crust
the graph above shows the composition of earths crust and the moons crust.

1. for which element is there the greatest difference between the percent by mass on the moon and the percent by mass on earth? explain your answer.
2. a common theory for the origin of the moon is that much of it is made of pieces of earth ejected after a collision with another celestial body. does the graph support this theory? explain your answer.

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Explanation:

Step1: Calculate mass - percent differences

For Oxygen: $|47 - 43|=4$
For Silicon: $|27 - 20| = 7$
For Magnesium: $|2 - 19|=17$
For Iron: $|5 - 10| = 5$
For Calcium: $|4 - 3|=1$
For Aluminum: $|8 - 3| = 5$
For Other Elements: $|7 - 2|=5$

Step2: Identify the element with the greatest difference

The greatest difference is 17, which is for Magnesium.

Step3: Analyze support for the moon - origin theory

The graph shows some similarities (e.g., presence of the same elements) and some differences in elemental composition between Earth's and Moon's crusts. While there are similarities that could suggest a connection, the significant differences (like the large difference in Magnesium percentage) mean the graph does not strongly support the theory that the moon is mostly made of Earth - ejected pieces.

Answer:

1. Magnesium. The difference in percent - by - mass between Earth's crust and the Moon's crust for Magnesium is 17, which is the largest among all elements.
2. No. Although there are some common elements, there are significant differences in the percentage of elements like Magnesium, indicating that the Moon is not simply made of pieces of Earth ejected after a collision.