Element Definition
An element is a pure chemical substance consisting of a single type of atom distinguished by its atomic number (number of protons). Elements cannot be broken down into simpler substances by chemical means.
Element Option Analysis
We need to identify which of the given options is a pure element:
- Air: This is a mixture of gases, primarily nitrogen and oxygen, along with other trace gases. It is not a single element.
- Sodium chloride: Commonly known as table salt (chemical formula NaCl), this is a compound made of sodium (Na) and chlorine (Cl) atoms chemically bonded together. It is not an element.
- Oxygen: This is a pure substance (chemical symbol O) composed only of oxygen atoms. It is listed on the periodic table and is a fundamental element.
- Water: This is a compound with the chemical formula H₂O, made of hydrogen (H) and oxygen (O) atoms chemically bonded. It is not an element.
Conclusion
Based on the analysis, Oxygen is the only substance listed that fits the definition of an element.
Important Questions from Basic Concepts of Chemistry
- Which one of the following is a chemical change?
Which one of the following methods can be used to separate anthracene from a mixture of salt and anthracene ?
Which among the following are essential constituents of Portland cement?
20 g of common salt is dissolved in 180 g of water. What is the mass percentage of the salt in the solution?
Combination of one volume of nitrogen with three volumes of hydrogen produces
