Class 9 NCERT Solutions Atoms and Molecules

Scroll down for PDF

Class 9 NCERT Solutions Atoms and Molecules - NCERT Solutions prepared for CBSE students by the best teachers in Delhi. 

Class IX Chapter 3 – Atoms and Molecules Science

Question 1:

In a reaction, 5.3 g of sodium carbonate reacted with 6 g of ethanoic acid. The products were 2.2 g of carbon dioxide, 0.9 g water and 8.2 g of sodium ethanoate. Show that these observations are in agreement with the law of conservation of mass.

Sodium carbonate + ethanoic acid → sodium ethanoate + carbon dioxide + water

Answer:

In the given reaction, sodium carbonate reacts with ethanoic acid to produce sodium ethanoate, carbon dioxide, and water.

Mass of sodium carbonate = 5.3 g (Given)

Mass of ethanoic acid = 6 g (Given)

Mass of sodium ethanoate = 8.2 g (Given)

Mass of carbon dioxide = 2.2 g (Given)

Mass of water = 0.9 g (Given)

Now, total mass before the reaction = (5.3 + 6) g

= 11.3 g

And, total mass after the reaction = (8.2 + 2.2 + 0.9) g

= 11.3 g

∴Total mass before the reaction = Total mass after the reaction

Hence, the given observations are in agreement with the law of conservation of mass.

 

Question 2:

Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas would be required to react completely with 3 g of hydrogen gas?

Answer:

It is given that the ratio of hydrogen and oxygen by mass to form water is 1:8. Then, the mass of oxygen gas required to react completely with 1 g of hydrogen gas is 8 g. Therefore, the mass of oxygen gas required to react completely with 3 g of hydrogen

gas is 8 × 3 g = 24 g.


Question 3:

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

Answer:

The postulate of Dalton’s atomic theory which is a result of the law of conservation of mass is:

Atoms are indivisible particles, which can neither be created nor destroyed in a chemical reaction.

Question 4:

Which postulate of Dalton’s atomic theory can explain the law of definite proportions?

Answer:

The postulate of Dalton’s atomic theory which can explain the law of definitevproportion is: The relative number and kind of atoms in a given compound remains constant.

 

 

Students should free download the NCERT solutions and get better marks in exams. Studiestoday.com panel of teachers recommend students to practice questions in NCERT books and download NCERT solutions.

Tags: 


Click on the text For more study material for Science please click here - Science

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

CBSE schools to have sports period daily for classes 1 to 12

CBSE schools to have sports period daily for classes 1 to 12, new curriculum introduced All work and no play makes a child dull. Nowadays students have a very hectic schedule so that they cannot take out time to play games and gently start ignoring sports. Therefore,...

CBSE Class 10 Board Exam 2020

CBSE Class 10 Board Exam 2020: Problems Students May Face In Choosing Subject The Central Board of Secondary Education (CBSE) class 10 board examination will start from February 2020. The Central Board of Secondary Education (CBSE) has started the process of filling...

CBSE Board Exams Changes to be implemented in exam pattern

CBSE Board Exams Class 10 & 12 2020: Changes to be implemented in exam pattern Are you appearing for the CBSE Class 10 and 12 Board Exams 2020? If yes, then you have to check out what CBSE has brought the major changes for the CBSE class 10 and 12 board exams 2020...

JEE Main registration 2020 List of qualifying exams

JEE Main registration 2020: List of qualifying exams The process of JEE (Joint Entrance Examination) Main has already been started from September 3, 2019, on the official website of JEE, i.e. jeemain.nic.in. The interested and eligible students can also apply for JEE...

CBSE class 10, 12 board exam important information

CBSE class 10, 12 board exam: important information to prevent problems for students : The Central Board of Secondary Education (CBSE) has issued an advisory for the students of class 10 and class 12 board. As per the notice, the registration of students appearing in...

Top Classroom Challenges According to the Teachers

Teacher plays a major role in our lives in the classrooms. Not only is studying, but the teacher also serves many other roles in the classrooms. A teacher is always a role model for a student who can inspire him to live a better future life. Besides this, life of a...

×
Studies Today