Most likely the second one (sand letting water run through it) because if you are trying to determine how what moves through soil You would want the one the one that can do that:)
Period 4 transition element that forms 2+ ion with a half‐filled d sub level is
Manganese (Mn)
What is the half-filled d sub-level?
Transition metals are an interesting and challenging group of elements. They have perplexing patterns of electron distribution that don’t always follow the electron-filling rules. Predicting how they will form ions is also not always obvious.
Transition metals belong to the d block, meaning that the d sublevel of electrons is in the process of being filled with up to ten electrons. Many transition metals cannot lose enough electrons to attain a noble-gas electron configuration. In addition, the majority of transition metals are capable of adopting ions with different charges. Iron, which forms either the Fe2+ or Fe3+ ions, loses electrons as shown below.
Some transition metals that have relatively few d electrons may attain a noble-gas electron configuration. Scandium is an example. Others may attain configurations with a full d sublevel, such as zinc and copper.
to know more about half-filled d sub-level
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Answer:
<h2>The answer is 3.2 g/L</h2>
Explanation:
The density of a substance can be found by using the formula

From the question
mass of cat = 400 g
volume = final volume of water - initial volume of water
volume = 125 - 100 = 25 L
The density of the cat is

We have the final answer as
<h3>3.2 g/L</h3>
Hope this helps you