Section A – Very Short Answer Questions (1 × 5 = 5 Marks) (Answer each question in one sentence) Define a chemical reaction. Give one example each of an exothermic and an endothermic reaction. What is the difference between a physical change and a chemical change?
Read MoreGeneral Chemical Names and Formulas Everyday Substances General Name Chemical Name Formula Water Hydrogen monoxide H₂O Common Salt / Table Salt Sodium Chloride NaCl Sand / Quartz Silicon dioxide SiO₂ Marble / Limestone Calcium Carbonate CaCO₃ Washing Soda Sodium Carbonate Na₂CO₃ Caustic Soda Sodium Hydroxide NaOH
Read MoreThe Taste Behind Food: Acids & Bases Ever wondered why lemons taste sour or soap feels bitter? It’s due to the presence of acids and bases in them. Acids Acids are substances that release hydrogen ions (H⁺) when dissolved in water. They usually taste sour. They
Read More.🧬 The Fundamental Unit of Life – Detailed Notes (Class 9) 🧠 Why Study Cells? Every living being, from a tiny bacterium to a huge whale, is made up of cells. These cells are the building blocks of life. Just like bricks form buildings, cells form
Read More1. Human Respiratory System and Its Organs The respiratory system facilitates gas exchange (O₂ in, CO₂ out). Key organs: A. Main Organs Organ Function Nose Air enters; hairs filter dust. Windpipe (Trachea) Tube carrying air to lungs. Bronchi Two branches leading to each lung. Lungs Spongy
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