Structural units of ice and dry ice are , respectively .

Options

A. `H_2 O, CO`
B. `H_2O, CO_2`
C. `CO_2, H_2O`
D. `CO, CO_2`

Answer

To solve the question regarding the structural units of ice and dry ice, we can follow these steps:

### Step 1: Understand the Composition of Ice
- Ice is the solid form of water. When water freezes, it forms a crystalline structure.
- The chemical formula for water is H₂O.

### Step 2: Identify the Structural Unit of Ice
- The structural unit of ice is therefore H₂O, as each molecule of ice is made up of water molecules.

### Step 3: Understand the Composition of Dry Ice
- Dry ice is the solid form of carbon dioxide (CO₂). It is commonly used as a refrigerant.
- When carbon dioxide is cooled to a solid state, it retains its molecular structure.

### Step 4: Identify the Structural Unit of Dry Ice
- The structural unit of dry ice is CO₂, as each molecule of dry ice is made up of carbon dioxide molecules.

### Step 5: Combine the Findings
- The structural units of ice and dry ice are H₂O and CO₂, respectively.

### Final Answer
- The structural units of ice and dry ice are, respectively, H₂O and CO₂.

---