Class 9 NCERT Solutions Atoms and Molecules with answers available in Pdf for free download. The NCERT Solutions for Class 9 Science with answers have been prepared as per the latest syllabus, NCERT books and examination pattern suggested in Standard 9 by CBSE, NCERT and KVS. Solutions to questions given in NCERT book for Class 9 Science are an important part of exams for Grade 9 Science and if practiced properly can help you to get higher marks. Refer to more Chapter-wise Solutions for NCERT Class 9 Science and also download more latest study material for all subjects
Atoms and Molecules Class 9 NCERT Solutions
Class 9 Science students should refer to the following NCERT questions with answers for Atoms and Molecules in standard 9. These NCERT Solutions with answers for Grade 9 Science will come in exams and help you to score good marks
Atoms and Molecules NCERT Solutions Class 9
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.
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