Uncommon Statement for Both Elements and Compounds: They can be broken down into simpler substances.

Explanation:
Elements and compounds are two types of substances that exist in nature. While they have some similarities, there are certain characteristics that differentiate them from each other. One such characteristic is their ability to be broken down into simpler substances.

Elements:
- Elements are pure substances that consist of only one type of atom.
- They cannot be broken down into simpler substances by any chemical means.
- Each element has its own unique set of properties, such as atomic number, atomic mass, and chemical reactivity.
- Elements can exist in various states (solid, liquid, gas) depending on the conditions of temperature and pressure.
- Examples of elements include hydrogen, oxygen, carbon, iron, and gold.

Compounds:
- Compounds are substances that are composed of two or more different elements chemically combined.
- They have a fixed composition and ratio of elements.
- Compounds can be broken down into simpler substances through chemical reactions.
- The breaking of compounds into simpler substances involves the breaking of chemical bonds between the atoms of different elements.
- Examples of compounds include water (H2O), carbon dioxide (CO2), sodium chloride (NaCl), and glucose (C6H12O6).

Uncommon Statement:
The statement "They can be broken down into simpler substances" is uncommon for both elements and compounds. This is because elements cannot be broken down into simpler substances, while compounds can be broken down into their constituent elements.

Elements:
- Elements are the simplest form of matter and cannot be broken down into simpler substances.
- They are the building blocks of all matter and cannot be further reduced or decomposed into other substances.
- Elements are classified into different categories based on their properties, such as metals, nonmetals, and metalloids.

Compounds:
- Compounds, on the other hand, can be broken down into simpler substances through chemical reactions.
- Chemical reactions involve the rearrangement of atoms and the breaking and formation of chemical bonds.
- For example, water (H2O) can be broken down into its constituent elements hydrogen (H) and oxygen (O) through a process called electrolysis.

In conclusion, while both elements and compounds are homogeneous substances and can be found free in nature, the ability to be broken down into simpler substances is an uncommon statement for both elements and compounds. Elements cannot be broken down further, while compounds can be broken down into their constituent elements through chemical reactions.

D) They can be broken down into simpler substances.
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