Argumentative essay examples grade 8

📚 Quick Study Guide

• ⚛️ Atoms: The basic building blocks of matter. Each element is made of only one type of atom.
• ➕ Elements: Substances that cannot be broken down into simpler substances by chemical means. Examples include oxygen (O), hydrogen (H), and carbon (C).
• 🤝 Compounds: Substances formed when two or more elements are chemically bonded together. Water ($H_2O$) and carbon dioxide ($CO_2$) are examples.
• ➗ Mixtures: Combinations of substances that are physically mixed but not chemically bonded. Air and seawater are examples.
• ⚖️ Chemical Reactions: Processes that involve the rearrangement of atoms and molecules to form new substances. They are represented by chemical equations.
• 🌡️ Acids and Bases: Acids have a pH less than 7, while bases have a pH greater than 7. Neutral substances have a pH of 7.
• 🔥 Combustion: A chemical process involving rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light.

🧪 Practice Quiz

1. Which of the following is an example of an element?
   1. Water ($H_2O$)
   2. Carbon (C)
   3. Salt (NaCl)
   4. Sugar ($C_{12}H_{22}O_{11}$)
2. What is the chemical formula for water?
   1. $CO_2$
   2. $O_2$
   3. $H_2O$
   4. NaCl
3. Which of the following is a mixture?
   1. Pure Gold (Au)
   2. Distilled Water ($H_2O$)
   3. Air
   4. Carbon Dioxide ($CO_2$)
4. What is the approximate pH of a neutral substance?
   1. 0
   2. 7
   3. 14
   4. 1
5. What process involves the rapid reaction of a substance with oxygen, producing heat and light?
   1. Melting
   2. Freezing
   3. Combustion
   4. Dissolving
6. Which of the following is an acid?
   1. Sodium Hydroxide (NaOH)
   2. Hydrochloric Acid (HCl)
   3. Ammonia ($NH_3$)
   4. Water ($H_2O$)
7. What are the basic building blocks of matter called?
   1. Molecules
   2. Compounds
   3. Elements
   4. Atoms