SEBA Class 9 Science Important Chapter 3 Atoms and Molecules

SEBA Class 9 Science Important Chapter 3 Atoms and Molecules Solutions English Medium As Per SEBA New Syllabus to each chapter is provided in the list so that you can easily browse through different chapters SEBA Class 9 General Science Additional Solutions and select need one. NCERT Important Solutions For Class 9 General Science Download PDF. Important Notes for Class 9 Science.

SEBA Class 9 Science Important Chapter 3 Atoms and Molecules

Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. Assam SEBA Board Class 9 Science Additional Question Answer are part of All Subject Solutions. Here we have given CBSE Class 9 Science Important Notes for All Chapters, You can practice these here.

Atoms and Molecules

Chapter: 3

IMPORTANT QUESTION ANSWER

Answer the Following Question:

1. What is the atomic mass of oxygen?

Ans: 16 u.

2. Give one example of a cation.

Ans: Na⁺ (Sodium ion).

3. What is a homogeneous mixture?

Ans: A mixture having a uniform composition throughout is called a homogeneous mixture. 

4. What is a heterogeneous mixture?

Ans. A mixture having non-uniform composition in different parts is called a heterogeneous mixture.

5. What is a saturated solution?

Ans. At any particular temperature, a solution that has dissolved as much solute as it is capable of dissolving, is said to be a saturated solution.

6. What is a suspension?

Ans. A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium.

7. What is Tyndall effect?

Ans. The scattering of a beam of light by colloidal particles is called Tyndall effect.

8. What is chromatography?

Ans. Chromatography is a technique used for separation of those solutes that dissolves in the same solvent.

9. What is fractional distillation?

Ans. The process used for separation of components of a mixture containing two or more miscible liquids having difference in boiling points less than 25 K is called fractional distillation.

10. What are the types of elements?

Ans. Metals, non-metals and metalloids.

11. State the Law of Conservation of Mass with an example.

Ans: The Law of Conservation of Mass states that mass can neither be created nor destroyed during a chemical reaction.

Example: When 5.3 g of sodium carbonate reacts with 6 g of acetic acid, the total mass of products (carbon dioxide, water, sodium acetate) remains 11.3 g, same as the reactants.

12. List any three postulates of Dalton’s Atomic Theory.

Ans: (i) All matter is made of atoms.

(ii) Atoms are indivisible and indestructible.

(iii) Atoms combine in simple whole-number ratios to form compounds.

13. Why can’t we see atoms with the naked eye?

Ans: Atoms are extremely small in size (about 10⁻¹⁰ m) and cannot be seen with the naked eye. Special microscopes like the scanning tunneling microscope are used.

14. Write two rules for writing chemical formula.

Ans: (i) The valencies of ions should balance.

(ii) The metal is written first, followed by the non-metal or polyatomic ion.

15. Write the names of the elements present in the following compounds:

(i) CaCO₃

Ans: CaCO₃ – Calcium, Carbon, Oxygen.

 (ii) HNO₃

Ans: HNO₃ – Hydrogen, Nitrogen, Oxygen.