Which of the following statements is true about gases under standard conditions?

• A. Gases have both a definite shape and a definite volume.
• B. Gases have a definite shape but no definite volume.
• C. Gases have a definite volume but no definite shape.
• D. Gases have no definite shape and no definite volume.

Answer: (D)

Verified step by step guidance

1. Recall the basic properties of gases compared to solids and liquids. Gases do not have a fixed shape or volume; they expand to fill the container they are in.
2. Understand that a definite shape means the substance maintains its shape without a container, which gases do not do—they take the shape of their container.
3. Recognize that a definite volume means the substance maintains a fixed volume regardless of the container, which gases also do not do—they expand or compress to fill the available space.
4. Compare the given statements to these properties: gases do not have definite shape or volume, so any statement claiming either is definite is false.
5. Conclude that the true statement about gases under standard conditions is that they have no definite shape and no definite volume.