A sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo

Options

A. a changein mass
B. a change in density
C. a change in composition
D. no change in physical properties

Explanation

To solve the question regarding the transformation of carbon dioxide (CO2) from solid to liquid and then to gas, we need to analyze the changes occurring during this process.

### Step-by-Step Solution:

1. **Identify the States of Matter**:
- Solid CO2 is commonly known as "dry ice".
- When dry ice is heated, it sublimates directly into gas, but if we consider the transformation through liquid, we first need to understand the phase changes.

2. **Phase Changes**:
- The transformation from solid to liquid is called **melting**.
- The transformation from liquid to gas is called **vaporization**.

3. **Understanding Density Changes**:
- In solids, particles are closely packed, resulting in a higher density.
- In liquids, particles are still close but can move around, resulting in a lower density compared to solids.
- In gases, particles are far apart, leading to the lowest density among the three states.

4. **Mass Consideration**:
- The mass of CO2 remains constant throughout the phase changes. For instance, 1 mole of solid CO2 (44 grams) will still be 44 grams when it melts into liquid and then vaporizes into gas.

5. **Composition**:
- The chemical composition of CO2 does not change during the phase transitions. It remains CO2 in all three states (solid, liquid, gas).

6. **Conclusion**:
- The transformation of CO2 from solid to liquid and then to gas involves a change in **density** and **physical state**, but not in mass or composition.

### Final Answer:
The sample of carbon dioxide that undergoes a transformation from solid to liquid and then to gas would undergo a **change in density** and a **change in physical state**.