Which of the following is commonly measured using a chemical test in the identification of ions and gases?

• A. The melting point of a compound
• B. The mass of a sample
• C. The atomic number of an element
• D. The presence of specific ions or gases in a sample

Answer: (D)

Verified step by step guidance

1. Understand that chemical tests are designed to detect the presence of specific ions or gases by producing observable changes such as color changes, precipitates, or gas evolution.
2. Recognize that physical properties like melting point or mass are measured using physical methods, not chemical tests.
3. Recall that the atomic number is a fundamental property of an element and is determined by the number of protons, not by chemical testing.
4. Identify that chemical tests are commonly used to confirm the presence of particular ions or gases in a sample by their characteristic reactions.
5. Conclude that the correct choice is the detection of specific ions or gases, as this aligns with the purpose of chemical tests in qualitative analysis.