Chemistry Class 8 ICSE FAQs
1. What are the basic concepts of chemistry that Class 8 ICSE students should know? |
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Ans. Class 8 ICSE students should understand the basic concepts of matter, elements, compounds, mixtures, chemical reactions, and the periodic table. Knowledge of physical and chemical changes, the states of matter, and simple chemical equations is also important.
2. What is an element in chemistry? |
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Ans. An element is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom and is represented by symbols on the periodic table, such as H for hydrogen and O for oxygen.
3. How do compounds differ from mixtures? |
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Ans. Compounds are substances formed when two or more elements chemically combine in fixed proportions, resulting in new properties. Mixtures, on the other hand, consist of two or more substances that are physically combined and can be separated without a chemical reaction.
4. What is the significance of the periodic table? |
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Ans. The periodic table organizes elements based on their atomic number, electron configuration, and recurring chemical properties. It helps students understand relationships between elements, predict chemical behavior, and identify trends in properties such as reactivity and electronegativity.
5. What are physical and chemical changes? |
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Ans. Physical changes are changes that affect one or more physical properties of a substance without altering its chemical composition, such as melting or boiling. Chemical changes result in the formation of new substances with different properties, like rusting of iron or combustion of wood.
6. Can you explain the law of conservation of mass? |
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Ans. The law of conservation of mass states that in a chemical reaction, the total mass of the reactants equals the total mass of the products. This means that matter cannot be created or destroyed, only transformed from one form to another during a chemical reaction.
7. What is a chemical equation? |
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Ans. A chemical equation is a symbolic representation of a chemical reaction, showing the reactants on the left side and the products on the right. It uses chemical formulas and coefficients to indicate the quantities of each substance involved.
8. What are acids and bases? |
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Ans. Acids are substances that release hydrogen ions (H⁺) in solution and have a sour taste, while bases release hydroxide ions (OH⁻) and have a bitter taste. Acids turn blue litmus paper red, and bases turn red litmus paper blue.
9. How do you identify a chemical change in a reaction? |
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Ans. Signs of a chemical change include color change, temperature change, gas production (bubbles), formation of a precipitate, or a change in odor. If any of these occur, a new substance is likely formed.
10. What is the role of a catalyst in a chemical reaction? |
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Ans. A catalyst is a substance that speeds up a chemical reaction without being consumed in the process. It lowers the activation energy needed for the reaction to occur, allowing it to proceed more quickly.
11. What are some common laboratory safety rules in chemistry? |
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Ans. Common laboratory safety rules include wearing safety goggles and gloves, handling chemicals carefully, knowing the location of emergency equipment, not eating or drinking in the lab, and following instructions from the teacher.
12. What is the process of distillation used for? |
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Ans. Distillation is a separation technique used to separate components of a mixture based on their boiling points. It is commonly used to purify liquids or separate liquid mixtures, such as separating water from saltwater.
13. How do temperature and pressure affect the states of matter? |
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Ans. Temperature and pressure can change the state of matter. Increasing temperature can turn solids into liquids (melting) or liquids into gases (evaporation), while increasing pressure can turn gases into liquids (condensation) or solids (sublimation).
14. What are the properties of metals and non-metals? |
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Ans. Metals are generally shiny, good conductors of heat and electricity, malleable, and ductile. Non-metals are usually dull, poor conductors, brittle in solid form, and can exist in various states at room temperature (solid, liquid, gas).
15. Why is it important to study chemistry in everyday life? |
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Ans. Studying chemistry is important as it helps us understand the composition and behavior of substances in our environment. It plays a crucial role in various fields such as medicine, environmental science, and industry, and helps us make informed decisions about health, safety, and sustainability.