A flask contain 84g of `CO_2` gas. Calculate how many moles of` CO_2` gas does it contain?

Options

A. 1.9 moles
B. 9 moles
C. 8 moles
D. None of these

Explanation

To calculate the number of moles of \( CO_2 \) gas in the flask, follow these steps:

### Step 1: Determine the mass of \( CO_2 \)
The mass of \( CO_2 \) given in the flask is 84 grams.

### Step 2: Calculate the molar mass of \( CO_2 \)
To find the molar mass of \( CO_2 \), we need to add the atomic masses of its constituent elements:
- Carbon (C) has an atomic mass of 12 g/mol.
- Oxygen (O) has an atomic mass of 16 g/mol, and since there are 2 oxygen atoms in \( CO_2 \), we calculate:

\[ \text{Molar mass of } CO_2 = \text{Atomic mass of C} + 2 \times \text{Atomic mass of O} = 12 + 2 \times 16 = 12 + 32 = 44 \text{ g/mol} \]

### Step 3: Use the formula to calculate moles
The number of moles of a substance can be calculated using the formula:

\[ \text{Number of moles} = \frac{\text{Given mass}}{\text{Molar mass}} \]

Substituting the values we have:

\[ \text{Number of moles} = \frac{84 \text{ g}}{44 \text{ g/mol}} \approx 1.91 \text{ moles} \]

### Step 4: Round the answer
The number of moles of \( CO_2 \) gas in the flask is approximately 1.91 moles.

### Final Answer
The flask contains approximately **1.91 moles of \( CO_2 \)** gas.

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