The number of moles of nitrogen present in one litre of air containing 19% nitrogen by volume, under standard condition, is:

Options

A. 5.83 x `10^(-3)`
B. 8.48 x `10^(-3)`
C. 7.83 x `10^(-3)`
D. 5.83 x `10^(-2)`

Explanation

To solve the problem of finding the number of moles of nitrogen in one liter of air containing 19% nitrogen by volume under standard conditions, we can follow these steps:

### Step 1: Understand the volume of nitrogen in the air
Given that the air contains 19% nitrogen by volume, we can calculate the volume of nitrogen in 1 liter of air.

\[ \text{Volume of nitrogen} = 19\% \text{ of } 1 \text{ liter} = 0.19 \text{ liters} \]

### Step 2: Use the ideal gas law to find the number of moles
At standard temperature and pressure (STP), 1 mole of an ideal gas occupies 22.4 liters. We can use this information to find the number of moles of nitrogen gas in the calculated volume.

\[ \text{Number of moles of nitrogen} = \frac{\text{Volume of nitrogen}}{\text{Volume occupied by 1 mole of gas at STP}} = \frac{0.19 \text{ liters}}{22.4 \text{ liters/mole}} \]

### Step 3: Calculate the number of moles
Now, we can perform the calculation:

\[ \text{Number of moles of nitrogen} = \frac{0.19}{22.4} \approx 0.00848 \text{ moles} \]

### Step 4: Final result
Thus, the number of moles of nitrogen present in one liter of air is approximately:

\[ \text{Number of moles of nitrogen} \approx 8.48 \times 10^{-3} \text{ moles} \]