Which of the following has maximum number of atoms?

Options

A. 18 g of `H_(2)O`
B. 16 g `O_(2)`
C. 4.4 g of `CO_(2)`
D. 16 g of `CH_(4)`

Answer

To determine which of the given substances has the maximum number of atoms, we will calculate the total number of atoms in each substance based on the given mass. We will consider the following substances:

1. 18 g of H2O
2. 16 g of O2
3. 4.4 g of CO2
4. 16 g of CH4

### Step-by-Step Solution

**Step 1: Calculate the number of atoms in 18 g of H2O.**

1. **Calculate moles of H2O:**
- Molecular weight of H2O = (2 × 1) + (1 × 16) = 18 g/mol
- Moles of H2O = Mass / Molar Mass = 18 g / 18 g/mol = 1 mol

2. **Calculate number of molecules:**
- Number of molecules = Moles × Avogadro's number = 1 mol × 6.022 × 10²³ = 6.022 × 10²³ molecules

3. **Calculate total number of atoms:**
- Each molecule of H2O has 3 atoms (2 H + 1 O).
- Total number of atoms = Number of molecules × 3 = 6.022 × 10²³ × 3 = 1.8066 × 10²⁴ atoms

**Step 2: Calculate the number of atoms in 16 g of O2.**

1. **Calculate moles of O2:**
- Molecular weight of O2 = 2 × 16 = 32 g/mol
- Moles of O2 = 16 g / 32 g/mol = 0.5 mol

2. **Calculate number of molecules:**
- Number of molecules = 0.5 mol × 6.022 × 10²³ = 3.011 × 10²³ molecules

3. **Calculate total number of atoms:**
- Each molecule of O2 has 2 atoms.
- Total number of atoms = Number of molecules × 2 = 3.011 × 10²³ × 2 = 6.022 × 10²³ atoms

**Step 3: Calculate the number of atoms in 4.4 g of CO2.**

1. **Calculate moles of CO2:**
- Molecular weight of CO2 = 12 + (2 × 16) = 44 g/mol
- Moles of CO2 = 4.4 g / 44 g/mol = 0.1 mol

2. **Calculate number of molecules:**
- Number of molecules = 0.1 mol × 6.022 × 10²³ = 6.022 × 10²² molecules

3. **Calculate total number of atoms:**
- Each molecule of CO2 has 3 atoms (1 C + 2 O).
- Total number of atoms = Number of molecules × 3 = 6.022 × 10²² × 3 = 1.8066 × 10²³ atoms

**Step 4: Calculate the number of atoms in 16 g of CH4.**

1. **Calculate moles of CH4:**
- Molecular weight of CH4 = 12 + (4 × 1) = 16 g/mol
- Moles of CH4 = 16 g / 16 g/mol = 1 mol

2. **Calculate number of molecules:**
- Number of molecules = 1 mol × 6.022 × 10²³ = 6.022 × 10²³ molecules

3. **Calculate total number of atoms:**
- Each molecule of CH4 has 5 atoms (1 C + 4 H).
- Total number of atoms = Number of molecules × 5 = 6.022 × 10²³ × 5 = 3.011 × 10²⁴ atoms

### Summary of Total Atoms:
- H2O: 1.8066 × 10²⁴ atoms
- O2: 6.022 × 10²³ atoms
- CO2: 1.8066 × 10²³ atoms
- CH4: 3.011 × 10²⁴ atoms

### Conclusion:
The substance with the maximum number of atoms is **16 g of CH4**, which has **3.011 × 10²⁴ atoms**.