1- There are four primary states of matter: solid, liquid, gas, and plasma.

– Solid: In this state, particles are closely packed together and have a fixed shape and volume. An example is ice. When a solid is heated, it can undergo a phase transition called melting, turning into a liquid.

– Liquid: Particles in a liquid are less tightly packed than in a solid, allowing them to flow and take the shape of their container. Water is an example. When a liquid is heated, it can undergo vaporization, turning into a gas. Conversely, when a liquid is cooled, it can freeze, turning back into a solid.

– Gas: In this state, particles are widely spaced and move freely, filling the entire volume of their container. An example is water vapor. When a gas is cooled, it can undergo condensation, turning into a liquid. If cooled further, it can become a solid through deposition.

– Plasma: This is an ionized state of matter, where electrons are separated from their parent atoms. It is found in stars, such as our sun. When a gas is heated to extremely high temperatures, it can become plasma. Conversely, when plasma is cooled, it can revert to a gaseous state through recombination.

2- The solar system is a collection of celestial bodies, including a star (our sun) and the objects that orbit it. There are eight planets in our solar system. Here they are, in order from the sun:

1. Mercury

2. Venus

3. Earth

4. Mars

5. Jupiter

6. Saturn

7. Uranus

8. Neptune

3- Electricity is a phenomenon that results from the presence and flow of electric charge. It involves the movement of electrons, which are negatively charged particles, through a conductive material.

There are two basic concepts in electricity: voltage and current. Voltage is the force that pushes electrons through a conductor, while current is the flow of electrons. Ohm’s law relates these two concepts with resistance, which is the opposition to the flow of electrons in a material.

Uses:-

Electricity is used in many aspects of everyday life. For example, it powers our homes, allowing us to use appliances like refrigerators, televisions, and computers. It also powers electric vehicles and is used in communication systems, such as telephones and the internet.