Rankers Physics
Topic: Thermal Physics
Subtopic: Thermodynamics

Find number of molecules of a gas at P = 1.4 × 107 N/m², T = 227°C and V = 2 × 10–³ m³ :
\[ 10\times 10^{24}\]
\[ 4.06\times 10^{24}\]
\[ 14\times 10^{30}\]
\[ 30\times 10^{20}\]

Solution:

To find the number of molecules \( N \) of a gas, we can use the ideal gas law in terms of the number of molecules:

\[
PV = NkT
\]

where:
- \( P = 1.4 \times 10^7 \, \text{N/m}^2 \)
- \( V = 2 \times 10^{-3} \, \text{m}^3 \)
- \( T = 227^\circ \text{C} = 227 + 273 = 500 \, \text{K} \)
- \( k = 1.38 \times 10^{-23} \, \text{J/K} \) (Boltzmann constant)

Rearrange to solve for \( N \):

\[
N = \frac{PV}{kT}
\]

Substitute the values:

\[
N = \frac{(1.4 \times 10^7) \times (2 \times 10^{-3})}{(1.38 \times 10^{-23}) \times 500}
\]

Calculating this:

\[
N \approx 4.06 \times 10^{24}
\]

So, the number of molecules is \( 4.06 \times 10^{24} \).

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