Pressure of 1 g of an ideal gas A at 27 | Class 11 Chemistry Chapter States of Matter, States of Matter NCERT Solutions

Previous / historical NCERT chapter

This chapter belongs to a previous NCERT/CBSE curriculum and is not part of the current 2026-27 chapter list. Removed in 2022-23.

Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter States of Matter. This page offers a step-by-step solution to the specific question from Exercise 1, Question 5:

Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

. With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 5:

Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B is introduced in the same flask at same temperature the pressure becomes 3 bar. Find a relationship between their molecular masses.

Answer:

Mass of gas A , WA = 1g

Mass of gas B,  WB = 2g

Pressure exerted by the gas A = 2 bar

Total pressure due to both the gases = 3 bar

In this case temperature & volume remain constant

Now if MA & MB are molar masses of the gases A & B respectively,therefore

pA V= WA RT/MA & Ptotal V = (WA/MA + WB/ MB) RT

= 2 X V = 1 X RT/MA & 3 X V = (1/MA + 2/MB)RT

From these two equations, we get

3/2 = (1/MA + 2/MB) / (1 /MA) = (MB + 2MA) / MB

This result in 2MA/ MB = (3/2) -1 = ½

OR MB = 4MA

Thus, a relationship between the molecular masses of A and B is given by

4MA = MB   


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  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about States of Matter.
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Comments

  • Sana
  • Oct 17, 2019

Why it can't be just p directly proportional to molecular weight by which mw1=2mw2


  • Rockstar
  • Sep 20, 2019

Greatest explanation


  • Samadrita
  • Jun 27, 2019

Thank you. Really helpful 😀


  • Lakshita joshi
  • Feb 27, 2019

R is here universal gas constant


  • Lakshita joshi
  • Feb 27, 2019

R is here universal gas constant


  • Niti
  • Nov 08, 2018

Why does the volume is constant here ... it is not given in question ..????


  • shiva tiwari allhabadi
  • Oct 30, 2018

W means n


  • shiva tiwari allhabadi
  • Oct 30, 2018

R means 0.281 atm


  • shiva tiwari allhabadi
  • Oct 30, 2018

Anita are u know the formula of mAss\molarmass =n and here n is represented by W 😕😕


  • Anita
  • Aug 13, 2018

What is meaning of wA/mA+wB/mB in this question please answer


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Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 5: Pressure of 1 g of an ideal gas A at 27 °C is found to be 2 bar. When 2 g of another ideal gas B....

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