NCERT Solutions for Class 8
NCERT solutions for class 8
Mathematics
Chapter 1: Rational Numbers
Definition: Rational numbers are numbers that can be expressed in the form p/q, where p and q are integers and q is not zero.
Formulas
- Addition of Rational Numbers: a/b + c/d = (ad + bc) / bd
- Subtraction of Rational Numbers: a/b - c/d = (ad - bc) / bd
- Multiplication of Rational Numbers: a/b * c/d = (ac) / (bd)
- Division of Rational Numbers: (a/b) / (c/d) = (a/b) * (d/c) = (ad) / (bc)
Examples
| Operation | Result |
|---|---|
| 1/2 + 1/3 | (1*3 + 2*1) / (2*3) = 5/6 |
| 1/2 - 1/3 | (1*3 - 2*1) / (2*3) = 1/6 |
| 1/2 * 1/3 | (1*1) / (2*3) = 1/6 |
| (1/2) / (1/3) | (1/2) * (3/1) = 3/2 |
Science
Chapter 2: Microorganisms: Friend and Foe
Definition: Microorganisms are tiny organisms that can only be seen with a microscope. They can be beneficial or harmful.
Examples of Beneficial Microorganisms
- Lactobacillus: Used in the production of yogurt.
- Rhizobium: Helps in nitrogen fixation in soil.
- Yeast: Used in baking and brewing.
Examples of Harmful Microorganisms
- Bacteria causing tuberculosis.
- Viruses causing flu.
- Fungi causing athlete's foot.
Examples
| Microorganism | Type | Use/Harm |
|---|---|---|
| Lactobacillus | Bacteria | Beneficial - Used in making yogurt |
| Rhizobium | Bacteria | Beneficial - Nitrogen fixation |
| Influenza virus | Virus | Harmful - Causes flu |
| Aspergillus | Fungus | Harmful - Causes respiratory issues |
Social Science
Chapter 3: Why Do We Need a Parliament?
Definition: The parliament is the supreme legislative body in a country, responsible for making laws and overseeing the government.
Functions of Parliament
- Law Making: Creating and passing laws.
- Control Over the Executive: Ensuring the government is functioning properly.
- Representation: Representing the interests of the citizens.
Examples
| Function | Explanation |
|---|---|
| Law Making | Debating and passing new laws to address current issues. |
| Control Over the Executive | Holding the government accountable through questions and discussions. |
| Representation | MPs voicing the concerns of their constituents in parliament. |
English
Chapter 4: The Best Christmas Present in the World
Summary: A story about the spirit of Christmas and the reconciliation between soldiers during World War I.
Key Points
- The discovery of a letter in an old desk.
- The story of a Christmas truce between British and German soldiers.
- The emotional impact of the letter on the recipient.
Example Analysis
Analyzing the themes of humanity and the impact of war on soldiers' lives, as portrayed through the Christmas truce.