Biology: Improvement in Food Resources
1. Why do we need food improvement?
o To get more food for a growing population.
o To make crops stronger against diseases and bad weather.
2. Manure and Fertilizers:
o Manure: Made from animal dung and plants. It improves soil naturally.
o Fertilizers: Made in factories (e.g., Urea). It gives plants special nutrients but can harm soil if
used too much.
3. Ways to Grow Crops Together:
o Mixed Cropping: Two crops grown together to use land better. Example: Wheat and Gram.
o Crop Rotation: Changing crops every season so soil doesn’t lose all its nutrients. Example: Rice
one season, then Beans.
4. Bio-fertilizers:
o Helpful tiny organisms like bacteria that make soil healthy. Example: Rhizobium, which helps
plants get nitrogen.
Physics: Work, Energy, and Power
1. What is Work?
o Work is done when you push or pull something, and it moves.
o Example: Pushing a toy car makes it move = Work done!
o Formula: Work = Force × Distance.
o Unit: Joule (J).
2. What is Energy?
o Energy is the ability to do work.
o Types of Energy:
Kinetic Energy: Energy when something is moving.
Example: A rolling ball.
Formula: KE=12mv2KE = \frac{1}{2}mv^2KE=21mv2
Potential Energy: Energy when something is in a position.
Example: Water in a dam before it falls.
Formula: PE=mghPE = mghPE=mgh
3. What is Power?
o Power is how fast work is done.
o Example: A faster car has more power than a slower car.
o Formula: Power = Work ÷ Time.
o Unit: Watt (W).
4. Law of Conservation of Energy:
o Energy never disappears; it just changes from one form to another.
o Example: A light bulb changes electrical energy into light and heat.
Chemistry: Atoms and Molecules
1. What are Atoms?
o Atoms are tiny particles that make up everything around us.
o Example: Water is made of tiny atoms of Hydrogen and Oxygen.
2. What are Molecules?
o When two or more atoms join together, they form a molecule.
o Example: Water (H₂O) has 2 Hydrogen atoms and 1 Oxygen atom.
3. Important Chemical Formulas:
o Water: H₂O
o Carbon Dioxide: CO₂
o Sodium Carbonate: Na₂CO₃
4. Dalton’s Atomic Theory (Simplified):
o Everything is made of tiny things called atoms.
o Atoms of the same material are exactly the same, but atoms of different materials are different.
Important Formulas:
1. Work = Force × Distance
o Example: Push a box with 5 N force for 2 m → Work = 5 × 2 = 10 J.
2. Kinetic Energy (KE) = 1/2mv2
Example: A ball (2 kg) moves at 3 m/s → KE = 1/2×2×32=9J
3. Potential Energy (PE) = mgh
o Example: A 1 kg book is on a table 2 m high → PE = 1×10×2=20J
5. Power = Work ÷ Time
Example: 50 J work done in 5 seconds → Power = 50÷5=10
WWhat is Molecular Mass?
The molecular mass of a substance is the total mass of all the atoms in one molecule of that substance.
It is measured in atomic mass units (u).
Example 1: Water (H₂O)
Formula: H₂O
Atomic mass of Hydrogen (H) = 1 u
Atomic mass of Oxygen (O) = 16 u
Now calculate:
2 atoms of Hydrogen = 2×1=2 u2 × 1 = 2 \, \text{u}2×1=2u
1 atom of Oxygen = 16 u16 \, \text{u}16u
Molecular mass of H₂O = 2 + 16 = 18 u
