Dry ice is

Options

A. solid `NH_(3)`
B. solid `SO_(2)`
C. solid `CO_(2)`
D. solid `N_(2)`

Explanation

To solve the question "Dry ice is," we need to identify which of the given options corresponds to dry ice. The options are:

1. Solid NH3 (Ammonia)
2. Solid SO2 (Sulfur Dioxide)
3. Solid CO2 (Carbon Dioxide)
4. Solid N2 (Nitrogen)

### Step-by-Step Solution:

**Step 1: Understand what dry ice is.**
- Dry ice is the solid form of carbon dioxide (CO2). It is produced by compressing CO2 gas and cooling it to a point where it solidifies.

**Hint for Step 1:** Remember that dry ice is specifically associated with carbon dioxide.

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**Step 2: Analyze the options provided.**
- We need to check which of the options represents solid CO2.
- Solid NH3 is ammonia, which is not dry ice.
- Solid SO2 is sulfur dioxide, which is also not dry ice.
- Solid CO2 is carbon dioxide, which is indeed dry ice.
- Solid N2 is nitrogen, which is not dry ice.

**Hint for Step 2:** Look for the chemical formula CO2 in the options.

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**Step 3: Confirm the properties of dry ice.**
- Dry ice sublimates at a temperature of approximately 194.7 K (or -78.5 °C). This is much colder than regular ice, which is 0 °C.
- Due to its low temperature, dry ice can cause cold burns if not handled properly.

**Hint for Step 3:** Recall the sublimation temperature of dry ice to differentiate it from other solids.

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**Step 4: Conclude the answer.**
- Based on the analysis, the correct answer is **solid CO2**.

### Final Answer:
Dry ice is **solid CO2** (option C).

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