Tamil Nadu Board of Secondary EducationSSLC (English Medium) Class 8th

# Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide chapter 12 - Atomic Structure [Latest edition]

## Chapter 12: Atomic Structure

Exercise
Exercise [Page 136]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Page 136]

Exercise | Q I. 1. | Page 136

The same proportion of carbon and oxygen in the carbon dioxide obtained from different sources proves the law of ______.

• reciprocal proportion

• definite proportion

• multiple proportion

• conservation of mass

Exercise | Q I. 2. | Page 136

Cathode rays are made up of

• neutral particles

• positively charged particles

• negatively charged particles

• None of the above

Exercise | Q I. 3. | Page 136

In water, hydrogen and oxygen are combined in the ratio of _____ by mass.

• 1:8

• 8:1

• 2:3

• 1:3

Exercise | Q I. 4. | Page 136

Which of the following statements made by Dalton has not undergone any change?

• Atoms cannot be broken.

• Atoms combine in small, whole numbers to form compounds.

• Elements are made up of atoms.

• All atoms of an elements are alike

Exercise | Q I. 5. | Page 136

In all atoms of an element

• the atomic and the mass number are same.

• the mass number is same and the atomic number is different.

• the atomic number is same and the mass number is different

• both atomic and mass numbers may vary

Exercise [Pages 136 - 137]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Pages 136 - 137]

#### Fill in the blanks.

Exercise | Q II. 1. | Page 136

______ is the smallest particle of an element.

Exercise | Q II. 2. | Page 137

An element is composed of ______ atoms.

Exercise | Q II. 3. | Page 137

An atom is made up of _______, ______ and _______.

Exercise | Q II. 4. | Page 137

A negatively charged ion is called _______, while positively charged ion is called _______.

Exercise | Q II. 5. | Page 137

_______ is a negatively charged particle.

• Electron

• Proton

Exercise | Q II. 6. | Page 137

Proton is deflected towards the _______ charged plate.

• positively

• negatively

Exercise [Page 137]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Page 137]

Exercise | Q III. | Page 137

Match the following.

 Law of conservation of mass Sir William Crookes Law of constant proportion James Chadwick Cathode rays Joseph Proust Anode rays Lavoisier Neutrons Goldstein
Exercise [Page 137]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Page 137]

Exercise | Q IV. 1. | Page 137

State the law of conservation of mass.

Exercise | Q IV. 2. | Page 137

State the law of constant proportions.

Exercise | Q IV. 3. | Page 137

Write the properties of anode rays.

Exercise | Q IV. 4. | Page 137

Define valency of an element with respect to hydrogen.

Exercise | Q IV. 5. | Page 137

Define the term ions or radicals.

Exercise | Q IV. 6. | Page 137

What is a chemical equation?

Exercise | Q IV. 7. | Page 137

Write the names of the following compounds.

1. CO
2. N2O
3. NO2
4. PCl5
Exercise [Page 137]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Page 137]

Exercise | Q V. 1. | Page 137

Find the valency of the element which is underlined in the following formula.

1. NaCl
2. CO2
3. Al (PO4)
4. Ba (NO3)2
5. CaCl2
Exercise | Q V. 2. | Page 137

Write the chemical formula for the following compounds

1. Aluminium sulphate
2. Silver nitrate
3. Magnesium oxide
4. Barium chloride
Exercise | Q V. 3. | Page 137

Write the skeleton equation for the following word equation and then balance them.

1. Carbon + Oxygen → Carbon dioxide.
2. Phosphorus + Chlorine → Phosphorus pentachloride.
3. Sulphur + Oxygen → Sulphur dioxide.
4. Magnesium + hydrogen → Magnesium + Hydrogen chloride chloride.
Exercise | Q V. 4. | Page 137

Balance the following chemical equation.

1. Na + O2 → Na2O3
2. Ca + N2 → Ca3N2
3. N2 + H2 →NH3
4. CaCO3 +HCl → CaCl2 + CO2 +H2O
5. Pb(NO3)2 → PbO + NO2 + O2
Exercise [Page 137]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide Chapter 12 Atomic StructureExercise [Page 137]

#### Higher Order Thinking Questions.

Exercise | Q VI. 1. | Page 137

Why does a light paddle wheel placed in the path of cathode rays begin to rotate, when cathode rays fall on it?

Exercise | Q VI. 2. | Page 137

How can we prove that the electrons carry a negative charge?

Exercise | Q VI. 3. | Page 137

Ruthresh, Hari, Kanishka, and Thahera collected different samples of water from a well, a pond, a river, and underground water. All these samples were sent to a testing laboratory. The test result showed the ratio of hydrogen to oxygen as 1:8.

1. What conclusion would you draw from the above experiment?
2. Which law of chemical combination does it obey?

Exercise

## Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide chapter 12 - Atomic Structure

Tamil Nadu Board Samacheer Kalvi solutions for Class 8th Science Answers Guide chapter 12 (Atomic Structure) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the Tamil Nadu Board of Secondary Education Class 8th Science Answers Guide solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 8th Science Answers Guide chapter 12 Atomic Structure are Atoms: Building Blocks of Matter, John Dalton’s Atomic Theory, Chemical Formula Or Molecular Formula, Laws of Chemical Combination, Sub-atomic Particles of Atom, Protons (p), Neutrons (n), Electrons (e), Valency and Its Types, Naming Chemical Compounds, J. J. Thomson’s Atomic model, Valency with Respect to Atoms, Law of Conservation of Mass, Variable Valency, Chemical Equation, Ions and It’s Types, Law of Constant Proportions, Balancing Chemical Equation.

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