Verified Solution • 2025–26 Session moderate

QJEEM23Phaa3c: JEE Main 2023 Physics - Class 11 JEEM23Phaa3c Solution: The root mean square speed of molecules of nitrogen gas at is…

The root mean square speed of molecules of nitrogen gas at 27∘C27^{\circ} \mathrm{C} is approximately : (Given mass of a nitrogen molecule =4.6×10−26 kg=4.6 \times 10^{-26} \mathrm{~kg} and take Boltzmann constant kB=1.4×10−23JK−1\mathrm{k}_{\mathrm{B}}=1.4 \times 10^{-23} \mathrm{JK}^{-1} )

Multiple Choice Options

  • A 91 m/s
  • B 1260 m/s
  • C 27.4 m/s
  • D 523 m/s

Step-by-Step Verified Solution

To find the root mean square speed of molecules of nitrogen gas, we can use the formula:

vrms=3kBTmv_{rms} = \sqrt{\frac{3k_BT}{m}}

where vrmsv_{rms} is the root mean square speed, kBk_B is the Boltzmann constant, TT is the temperature in Kelvin, and mm is the mass of a nitrogen molecule.

First, we need to convert the temperature from Celsius to Kelvin:

T=27∘C+273=300 KT = 27^{\circ}\mathrm{C} + 273 = 300\,\mathrm{K}

Now, substitute the given values of kBk_B , TT , and mm into the formula:

vrms=3(1.4×10−23 JK−1)(300 K)4.6×10−26 kgv_{rms} = \sqrt{\frac{3(1.4 \times 10^{-23}\, \mathrm{JK}^{-1})(300\,\mathrm{K})}{4.6 \times 10^{-26}\,\mathrm{kg}}}

Simplify and calculate the root mean square speed:

vrms=523 m/sv_{rms} = 523\,\mathrm{m/s}

The root mean square speed of molecules of nitrogen gas at 27∘C27^{\circ}\mathrm{C} is 523 m/s.

Related Learning Resources & Exam Preparation