Which substance can be decomposed by a chemical change? a. calcium b. potassium c. sodium d. sodium chloride
The correct answer and explanation is:
Correct Answer: d. sodium chloride
Sodium chloride (NaCl), commonly known as table salt, is a compound made of two elements: sodium (Na) and chlorine (Cl). It can be decomposed by a chemical change through a process such as electrolysis. This process involves passing an electric current through molten or aqueous sodium chloride to break the chemical bonds between sodium and chlorine atoms. As a result, elemental sodium and chlorine gas are produced. This transformation is a chemical change because it alters the composition of the original substance, forming entirely different substances with different chemical properties.
On the other hand, the other options—calcium, potassium, and sodium—are all elements. Elements are the simplest forms of matter that cannot be broken down into simpler substances by chemical means. Chemical changes involve the rearrangement of atoms in compounds or molecules, but elements consist of only one type of atom. Therefore, calcium, potassium, and sodium cannot be chemically decomposed because they are already in their simplest chemical form.
The ability of a substance to undergo decomposition by chemical means is a characteristic of compounds, not elements. Compounds contain two or more elements that are chemically bonded, making it possible to separate them through chemical reactions. Sodium chloride is a prime example of this. When decomposed, it yields its constituent elements, each of which has very different properties. Sodium is a soft, highly reactive metal, while chlorine is a greenish-yellow toxic gas.
Thus, the correct and most scientifically accurate answer is sodium chloride, as it can be chemically decomposed into simpler substances, unlike the elements listed in the other choices.