NCERT Solutions for Grade 9 Science Chapter 3 Atoms and Molecules
NCERT Solutions for Class 9 Science Chapter 3 Atoms and Molecules
May 03, 2023
2
1. In this reaction, 5.3 gram of sodium carbonate reacted with 6 gram of ethanoic acid. The products were 2.2 gram of a carbon dioxide, 0.9 gram water and 8.2 gram of a sodium ethanoate. Show that this observations are in agreement with a law of a conservation of a mass.
Sodium carbonate + ethanoic acid-sodium ethanoate + carbon dioxide + water
Ans :
In a this response, sodium carbonate responds with a acidic corrosive to create a sodium acetic acid derivation, carbon dioxide and water.
Sodium Carbonate + Acidic Corrosive - Sodium Acetic acid derivation + Carbon Dioxide + Water
Sodium Carbonate Mass = 5.3 g (cat) Acetic Acid Mass = 6 g (cat) Sodium Acetate Mass = 8.2 g (fold) Carbon more excess Silica = 2.2 g (given) Water mass = 0.
9 g (Given)
Now, total mass before reaction = (5.3 + 6) g
= 11.3g
and total mass after reaction = (8.2 + 2.2 + 0.
9) g = 11.3 g
Total mass reaction before Total mass reaction after
Therefore, the analysis given is based on the law of conservation of mass.
2. Hydrogen and the oxygen is combine in a ratio of 1:8 by mass to form a water. How much oxygen is needed to complete the reaction with 3 g of hydrogen?
Answer
Next, 8 g of oxygen is required to complete the reaction of 1 g of hydrogen.
The mass of oxygen required to complete 3 grams of hydrogen is approximately 8*3 grams 28
3. The postulate of Dalton's atomic theory is the result of the law of conservation of mass ?
Answer
Dalton's conjecture: "Atoms are indivisible particles that cannot be created or destroyed in chemical reactions", the result of the law of conservation of mass.
4. Which postulate of Dalton's atomic theory can explain the true rate law?
Answer
Dalton's theory that "the relative numbers and types of atoms in a compound are constant" can explain the law of exact proportions.
1. Define atomic mass unit.
Answer
A unit of mass equal to one twelfth of the mass of a carbon-12 atom is called an atomic mass unit. It's spelled "you".
2. Why is it not possible to see an atom with naked eyes?
Answer
Atoms are so small that they cannot be seen with the naked eye. Also, the atoms of the elements do not exist independently.
1. Write down the formulae of
(i) sodium oxide
► Na₂O
(ii) aluminium chloride
► AlCl3
(iii) sodium sulphide
► Na₂S
(iv) magnesium hydroxide -
►Mg(OH)2
2. Write down the names of compounds represented by the following formulae:
Answer
(i) Al2(SO4)3
►Aluminium sulphate
(ii) CaCl2
► Calcium chloride
(iii) K₂SO4
►Potassium sulphate
(iv) KNO
►Potassium nitrate
(v) CaCO
► Calcium carbonate
3. What is meant by the term chemical formula?
Answer
The chemical equation of a compound may be a typical representation of its composition.
4. How many atoms are present in a
(i) H2S molecule and
(ii) PO₁ion?
Answer
(i) There are three atoms in the H2S molecule; two hydrogens and one sulfur.
(ii) There are five atoms in the PO4³ ion; one phosphorus and four oxygens.
Thank You
ReplyDeleteThank you very much 😊
ReplyDelete