What are Exothermic reactions

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Exothermic reactions are chemical processes that release energy, typically as heat, into the surroundings.

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The equation of potassium with water is

potassium + water --> potassium hydroxide + hydrogen

Microorganisms are tiny living things that cannot be seen with our eyes. They include bacteria and fungi. These microorganisms play an important role in decay. Decay means the breaking down of dead plants, dead animals, food scraps, and other organic materials.

When something dies or falls to the ground, microorganisms start to feed on it. As they feed, they break the material into smaller and simpler substances. This process releases nutrients back into the soil.

The Nervous System

The nervous system is one of the most important systems in our body. It helps us feel, move, think, and respond to what is happening around us. It acts like the contrl centerol for our whole body.

Main Parts:

1. Brain:

   • The main control center.

   • It helps us think, learn, remember, and make decisions.

Liquid Pressure

• Liquid pressure is the force that a liquid exerts on the walls or bottom of its container.

• It is caused by the weight of the liquid and acts in all directions.

• The deeper you go, the greater the pressure — because more liquid is above that point.

• Example: When you dive deeper into a swimming pool, you feel more pressure on your ears — that’s liquid pressure increasing with depth.

Gas Pressure

Price Elasticity of Supply (PES)

• Definition: PES measures how much the quantity supplied of a good changes when its price changes.

• Formula:

  

• Elastic Supply (PES > 1): Supply changes more than price.

• Inelastic Supply (PES < 1): Supply changes less than price.

Concave and convex lenses are two types of lenses that refract light differently due to their shape. A convex lens is thicker at the center, causing parallel light rays to converge to a focal point, and is also known as a converging lens. A concave lens is thinner at the center, causing parallel light rays to diverge, and is also called a diverging lens.

Convex lens

Shape: Thicker at the center and thinner at the edges.

Function: Converges parallel light rays to a single focal point.

Focal Length: Positive.

Uses: Magnifying glasses, cameras, microscopes, and for correcting farsightedness (hypermetropia).

• ozone is a gas

• their is a layer of ozone high up in the atmosphere

• the ozone layer is 25 km of the ground

• the sun sends out ultraviolet rays it can harm living organisms

• the ozone layer reduces the ultraviolet ray that reaches the ground

• in 1985 scientists discovered that their is less ozone layer in the antarctic

🌱 what is a kingdom?

a kingdom is a big group scientists made to sort all living things.every plant, animal, fungus, and tiny germ belongs to one of these five kingdoms.they are grouped by how they eat, grow, and build their body.

🦠 1. Monera – the first life

these are tiny single-celled beings — the oldest life on Earth.they have no nucleus (so their DNA just floats around).they live everywhere — in soil, hot springs, even inside you.

examples: bacteria, cyanobacteria (blue-green algae).

they:

🐸 Amphibians

Amphibians are animals that live two kinds of lives — one in water and one on land.The word “amphibian” means “double life.”

🧬 how they grow

When they are born, they start life in water as larvae (like tadpoles).They breathe with gills like fish and swim using a tail.Then, as they grow up, they go through a change called metamorphosis —their gills turn into lungs, their tails shrink, and they grow legs for land.

💧 why they need water

Even when they live on land, their skin must stay wet.Their skin helps them breathe oxygen directly from air or water.If their skin dries, they can suffocate.That’s why you’ll see frogs, salamanders, and newts in damp places.