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QJEEM23Ph5e61: JEE Main 2023 Physics - Class 11 JEEM23Ph5e61 Solution: The rms speed of oxygen molecule in a vessel at particular…

The rms speed of oxygen molecule in a vessel at particular temperature is (1+5x)12v\left(1+\frac{5}{x}\right)^{\frac{1}{2}} v , where vv is the average speed of the molecule. The value of xx will be:

(\left(\right. Take π=227)\left.\pi=\frac{22}{7}\right)

Multiple Choice Options

  • A 4
  • B 8
  • C 28
  • D 27

Step-by-Step Verified Solution

The relationship between the root-mean-square (rms) speed ( vrmsv_{rms} ) and the average speed ( vavgv_{avg} ) of molecules in a gas can be found using the Maxwell-Boltzmann distribution. The rms speed and average speed are related as follows:

vrms=3RTMv_{rms} = \sqrt{\frac{3RT}{M}} vavg=8RTπMv_{avg} = \sqrt{\frac{8RT}{\pi M}}

Where:

  • RR is the ideal gas constant
  • TT is the temperature in Kelvin
  • MM is the molar mass of the gas
  • π\pi is the mathematical constant pi

In this problem, the rms speed of the oxygen molecule is given by:

vrms=(1+5x)12vavgv_{rms} = \left(1+\frac{5}{x}\right)^{\frac{1}{2}} v_{avg}

Now, let's divide the expression for vrmsv_{rms} by the expression for vavgv_{avg} :

vrmsvavg=3RTM8RTπM=(1+5x)12\frac{v_{rms}}{v_{avg}} = \frac{\sqrt{\frac{3RT}{M}}}{\sqrt{\frac{8RT}{\pi M}}} = \left(1+\frac{5}{x}\right)^{\frac{1}{2}}

By simplifying the expression, we get:

vrmsvavg=38π=(1+5x)12\frac{v_{rms}}{v_{avg}} = \frac{\sqrt{3}}{\sqrt{\frac{8}{\pi}}} = \left(1+\frac{5}{x}\right)^{\frac{1}{2}}

Square both sides of the equation:

38π=1+5x\frac{3}{\frac{8}{\pi}} = 1 + \frac{5}{x}

Now we will substitute the provided value of π=227\pi = \frac{22}{7} :

38227=1+5x\frac{3}{\frac{8}{\frac{22}{7}}} = 1 + \frac{5}{x}

By simplifying the expression, we get:

3⋅2278=1+5x\frac{3 \cdot \frac{22}{7}}{8} = 1 + \frac{5}{x}

Now let's solve for xx :

6656−1=5x\frac{66}{56} - 1 = \frac{5}{x} 1056=5x\frac{10}{56} = \frac{5}{x}

Multiplying both sides by xx :

1056x=5\frac{10}{56}x = 5

Finally, solving for xx :

x=5⋅5610=28x = \frac{5 \cdot 56}{10} = 28

So, the value of xx is 28\boxed{28} .

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