Which statement about gases is most accurate?

• A. Gases are less compressible than solids and liquids.
• B. Gases have a definite shape and volume.
• C. At constant temperature and pressure, equal volumes of different gases contain the same number of molecules.
• D. The density of a gas increases as temperature increases, assuming pressure is constant.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the properties of gases compared to solids and liquids. Gases are generally much more compressible than solids and liquids because their particles are far apart and can be pushed closer together.
2. Step 2: Recall that gases do not have a definite shape or volume; they expand to fill the container they are in, unlike solids and liquids which have fixed shapes or volumes.
3. Step 3: Review Avogadro's Law, which states that at constant temperature and pressure, equal volumes of different gases contain the same number of molecules. This is a fundamental principle in gas behavior.
4. Step 4: Consider the relationship between gas density, temperature, and pressure. According to the ideal gas law, if pressure is constant and temperature increases, the volume increases, causing the density (mass/volume) to decrease, not increase.
5. Step 5: Based on these concepts, identify the most accurate statement as the one related to Avogadro's Law: 'At constant temperature and pressure, equal volumes of different gases contain the same number of molecules.'