Calculate the mole fraction of benzene i | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

Question:

Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4

Answer:

Molecules are made up of atoms & are  quite small, therefore the actual mass of a molecule cannot be detrmined.It is expressed as the relative mass.C-12 isotope is used to express the relative molecular masses of substances.Thus  molecular mass of a substance may be defined as: the average relative mass of its molecule as compared to the mass of carbon atom taken as 12 amu.

(i) H2O:

The molecular mass of water, H2O

= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)

= [2(1.0084) + 1(16.00 u)]

= 2.016 u + 16.00 u

= 18.016

= 18.02 u

(ii) CO2:

The molecular mass of carbon dioxide, CO2

= (1 × Atomic mass of carbon) + (2 × Atomic mass of oxygen)

= [1(12.011 u) + 2 (16.00 u)]

= 12.011 u + 32.00 u

= 44.01 u

(iii) CH4:

The molecular mass of methane, CH4

= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)

= [1(12.011 u) + 4 (1.008 u)]

= 12.011 u + 4.032 u

= 16.043 u


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Solutions.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

Comments

  • Aadil
  • 2021-02-27 15:00:27

Sir please tell me 0.385/(0.385+0.454


  • Andria
  • 2020-09-02 12:55:33

Thankyou sir


  • Swati
  • 2020-03-02 21:04:15

Very very helpful


  • Bhanu
  • 2019-12-28 10:03:06

Thanks


  • Sami sonare
  • 2019-11-16 17:05:00

Thank you sir


  • Mohammadi Shafiya
  • 2019-10-09 10:28:23

Thanks a lot😃!


  • Rishabh Singh Rajput
  • 2019-09-12 19:44:58

Thanks sir


  • Nidhi
  • 2019-08-19 20:02:59

Really helpful ✌️


  • Prince
  • 2019-07-18 17:08:00

MainBoling sir


  • Aaryan
  • 2019-07-18 13:24:21

Which is solute nd solvent


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 2: Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.....