Welcome to TNPSC Chemistry Test 5, focusing on Elements and Compounds in Everyday Life. This test covers common elements, common compounds, their important uses and properties, chemical names and formulas, and everyday applications. The questions are designed to help TNPSC aspirants revise important Chemistry Elements and Compounds concepts and strengthen their exam preparation through practical and exam-oriented questions
Note: Review the detailed explanations after attempting the test to better understand the questions and reinforce the important points covered in this topic.
Important Elements and Compounds in Everyday Life Test 5 – Study Notes & Quick Revision
This TNPSC Chemistry Test 5 provides a detailed revision of Elements and Compounds, with a focus on their importance in everyday life. The explanations cover common elements and common compounds, their uses and properties, important chemical names and formulas, and everyday applications of familiar substances. Each question is explained clearly to help you understand the underlying Chemistry concepts, remember important facts, and improve your performance in TNPSC examinations.
1. Which metal is commonly used for making electrical wires?
Answer: A. Copper
Explanation
Copper is commonly used for making electrical wires because it is a very good conductor of electricity and has high ductility, which allows it to be drawn into thin wires. It is also durable and resistant to corrosion, making it suitable for household wiring, electrical appliances, and other electrical connections.
Key Points
- Copper is a good conductor of electricity.
- Copper is highly ductile.
- It is widely used in electrical wiring.
- Copper is a metal.
Real-Life Example : Copper wires are commonly used inside household electrical cables to carry electricity to switches, sockets, and electrical appliances.
2. Which element is commonly used for making aluminium foil and utensils?
Answer: B. Aluminium
Explanation
Aluminium is widely used for making foil and utensils because it is lightweight, malleable, and a good conductor of heat. Its malleability allows it to be pressed into very thin sheets, making it suitable for aluminium foil. It is also resistant to corrosion, which makes aluminium useful for cooking utensils and many household products.
Key Points
- Aluminium is a metal.
- It is lightweight and malleable.
- Aluminium is a good conductor of heat.
- It is resistant to corrosion.
- It is commonly used for foil and utensils.
Real-Life Example : Aluminium foil is commonly used to wrap and store food, while aluminium utensils are used for cooking.
3. Which element is commonly used in graphite form in pencil leads?
Answer: C. Carbon
Explanation
Carbon exists in different forms called allotropes, including graphite and diamond. Graphite is a form of carbon and is used in pencil leads because its layers can slide over one another and leave a mark on paper. Pencil leads are generally made from a mixture of graphite and clay, with the proportion of these materials affecting the hardness of the pencil.
Key Points
- Carbon is a non-metal.
- Graphite is an allotrope of carbon.
- Diamond is another allotrope of carbon.
- Graphite is used in pencil leads.
- Pencil leads generally contain graphite and clay.
Real-Life Example : When you write with a pencil, graphite from the pencil lead is deposited onto the paper, producing the written mark.
4. Which element is commonly used to disinfect drinking water?
Answer: A. Chlorine
Explanation
Chlorine is commonly used to disinfect drinking water because it can destroy or inactivate many harmful microorganisms, including bacteria and viruses. It is added to water in controlled amounts during water treatment to make the water safer for drinking. Chlorine-based compounds are also widely used for disinfecting water supplies.
Key Points
- Chlorine is a chemical element.
- It is widely used for water disinfection.
- Chlorine helps destroy harmful microorganisms.
- It is used in controlled amounts during water treatment.
Real-Life Example : Chlorine is used in municipal water treatment plants to disinfect water before it is supplied to homes.
5. Which element is an important component of many fertilizers?
Answer: A. Nitrogen
Explanation
Nitrogen is an important element required for plant growth and is a major component of many fertilizers. Plants need nitrogen for the formation of proteins and chlorophyll, which are essential for healthy growth and photosynthesis. Nitrogen-containing fertilizers help supply this important nutrient to crops.
Key Points
- Nitrogen is a chemical element.
- It is an essential nutrient for plants.
- Nitrogen is a component of many fertilizers.
- It is important for protein and chlorophyll formation.
Real-Life Example : Farmers use nitrogen-containing fertilizers to provide crops with the nitrogen needed for healthy growth.
6. Which compound is commonly known as baking soda?
Answer: C. Sodium hydrogen carbonate
Explanation
Sodium hydrogen carbonate is the chemical name for baking soda. It is a white, crystalline compound that is commonly used in baking because it releases carbon dioxide when it reacts with an acid, helping dough and batter rise. It is also used in some cleaning and household applications.
Key Points
- Baking soda is sodium hydrogen carbonate.
- It is a compound.
- It releases carbon dioxide when it reacts with an acid.
- It is commonly used in baking.
Real-Life Example : Baking soda is added to cakes and other baked foods to help make them light and soft.
7. What is the chemical formula of baking soda?
Answer: B. NaHCO₃
Explanation
The chemical formula of baking soda is NaHCO₃, which represents sodium hydrogen carbonate. In this formula, Na represents sodium, H represents hydrogen, C represents carbon, and O represents oxygen. Baking soda is commonly used in baking and also has several household applications.
Key Points
- Baking soda is sodium hydrogen carbonate.
- Its chemical formula is NaHCO₃.
- It contains sodium, hydrogen, carbon, and oxygen.
- It is commonly used in baking.
Real-Life Example : When baking soda reacts with an acidic ingredient in a cake mixture, it produces carbon dioxide gas, which helps the mixture rise.
8. Which compound is commonly known as washing soda?
Answer: C. Sodium carbonate decahydrate
Explanation
Washing soda is the common name for sodium carbonate decahydrate, with the chemical formula Na₂CO₃·10H₂O. It is a crystalline compound that is commonly used for cleaning and in some industrial processes. Washing soda is also useful in the treatment of hard water because it can remove certain calcium and magnesium ions.
Key Points
- Washing soda is sodium carbonate decahydrate.
- Its chemical formula is Na₂CO₃·10H₂O.
- It is a hydrated salt.
- It is commonly used as a cleaning agent.
- It is useful in softening hard water.
Real-Life Example : Washing soda can be used as a household cleaning agent and for removing grease and dirt from clothes and surfaces.
9. Which compound is used for removing permanent hardness of water?
Answer: A. Washing soda
Explanation
Washing soda is used to remove the permanent hardness of water because it reacts with dissolved calcium and magnesium salts and converts them into insoluble carbonates. These insoluble substances can then be separated from the water. Therefore, washing soda is an important compound used for softening hard water.
Key Points
- Washing soda is used to soften hard water.
- It helps remove permanent hardness.
- It reacts with calcium and magnesium salts.
- Insoluble carbonates are formed during the process.
- Washing soda is sodium carbonate decahydrate.
Real-Life Example : Washing soda can be used in water treatment processes to reduce hardness caused by dissolved calcium and magnesium salts.
10. Which compound is commonly known as bleaching powder?
Answer: B. Calcium oxychloride
Explanation
Bleaching powder is commonly known as calcium oxychloride and is generally represented by the formula CaOCl₂. It is a white or pale yellowish powder with a characteristic chlorine-like smell. It is widely used as a bleaching agent and for disinfecting drinking water because it releases chlorine.
Key Points
- Bleaching powder is commonly known as calcium oxychloride.
- Its commonly used formula is CaOCl₂.
- It releases chlorine.
- It is used as a bleaching agent.
- It is used for disinfecting drinking water.
Real-Life Example : Bleaching powder is used in water treatment to help disinfect drinking water and make it safer for use.
11. Which compound is commonly used for making casts for fractured bones?
Answer: C. Plaster of Paris
Explanation
Plaster of Paris is commonly used for making casts for fractured bones because it can be moulded into the required shape and then hardens when mixed with water. It is made from calcium sulphate hemihydrate and has the chemical formula CaSO₄·½H₂O. When mixed with water, it changes into gypsum and forms a hard mass that can support and immobilize the injured part.
Key Points
- Plaster of Paris is a compound.
- It is calcium sulphate hemihydrate.
- Its formula is CaSO₄·½H₂O.
- It hardens when mixed with water.
- It is used for making casts for fractured bones.
Real-Life Example : A plaster cast can be placed around a fractured arm or leg to keep the injured bone in a stable position while it heals.
12. Plaster of Paris is chemically known as
Answer: A. Calcium sulphate hemihydrate
Explanation
Plaster of Paris is chemically known as calcium sulphate hemihydrate, with the chemical formula CaSO₄·½H₂O. It is produced by heating gypsum, which is calcium sulphate dihydrate, to remove part of its water of crystallization. When Plaster of Paris is mixed with water, it changes back into gypsum and hardens.
Key Points
- Plaster of Paris is calcium sulphate hemihydrate.
- Its chemical formula is CaSO₄·½H₂O.
- It is prepared by heating gypsum.
- Gypsum is calcium sulphate dihydrate.
- Plaster of Paris hardens when mixed with water.
Real-Life Example : Plaster of Paris is used for making casts, moulds, decorative items, and supporting fractured bones.
13. Which compound is commonly present in vinegar?
Answer: B. Acetic acid
Explanation
Acetic acid is the main acid present in vinegar and gives vinegar its characteristic sour taste and smell. Household vinegar generally contains a dilute solution of acetic acid in water. Acetic acid is also known as ethanoic acid and has the chemical formula CH₃COOH.
Key Points
- Acetic acid is commonly present in vinegar.
- It is also called ethanoic acid.
- Its chemical formula is CH₃COOH.
- Vinegar contains dilute acetic acid.
- Acetic acid gives vinegar its sour taste.
Real-Life Example : Vinegar is commonly used in cooking, food preservation, and salad dressings.
14. Which compound is commonly used as an antacid?
Answer: A. Sodium hydrogen carbonate
Explanation
Sodium hydrogen carbonate, commonly known as baking soda, can be used as an antacid because it reacts with excess hydrochloric acid in the stomach and helps neutralize it. This can provide temporary relief from acidity and indigestion. Its chemical formula is NaHCO₃.
Key Points
- Sodium hydrogen carbonate is also called baking soda.
- Its chemical formula is NaHCO₃.
- It is a mild alkaline compound.
- It can neutralize excess stomach acid.
- It can be used as an antacid.
Real-Life Example : Sodium hydrogen carbonate may be used in some antacid preparations to provide temporary relief from acidity.
15. Which gas is commonly used in soda-acid fire extinguishers?
Answer: C. Carbon dioxide
Explanation
Carbon dioxide is the gas produced in a soda-acid fire extinguisher. In this type of extinguisher, sodium hydrogen carbonate reacts with an acid to produce carbon dioxide gas. Carbon dioxide does not support combustion and can help smother the fire by reducing the contact between the fire and oxygen.
Key Points
- Carbon dioxide is produced in soda-acid fire extinguishers.
- It does not support combustion.
- It is produced by a chemical reaction inside the extinguisher.
- Carbon dioxide helps smother the fire.
- Sodium hydrogen carbonate is involved in the reaction.
Real-Life Example : A soda-acid fire extinguisher can produce carbon dioxide to help put out certain small fires.
16. Which compound is commonly known as quicklime?
Answer: B. Calcium oxide
Explanation
Calcium oxide is commonly known as quicklime or burnt lime, and its chemical formula is CaO. It is a white, solid compound prepared by heating limestone, which is mainly calcium carbonate. Calcium oxide reacts vigorously with water to form calcium hydroxide, commonly known as slaked lime.
Key Points
- Quicklime is calcium oxide.
- Its chemical formula is CaO.
- It is prepared by heating limestone.
- It reacts with water to form calcium hydroxide.
- Calcium hydroxide is known as slaked lime.
Real-Life Example : Quicklime is used in construction materials and in some industrial processes, including the manufacture of cement.
17. Which compound is commonly known as slaked lime?
Answer: C. Calcium hydroxide
Explanation
Calcium hydroxide is commonly known as slaked lime, and its chemical formula is Ca(OH)₂. It is formed when calcium oxide, or quicklime, reacts with water. Calcium hydroxide is a basic compound and has several uses in construction, water treatment, and other industrial applications.
Key Points
- Slaked lime is calcium hydroxide.
- Its chemical formula is Ca(OH)₂.
- It is formed by reacting quicklime with water.
- Calcium hydroxide is a base.
- It has several uses in construction and water treatment.
Real-Life Example : Slaked lime is used in construction for preparing mortar and other building materials.
18. Which gas is the major combustible component of biogas?
Answer: B. Methane
Explanation
Methane is the major combustible component of biogas and is responsible for its ability to produce heat and energy when burned. Biogas is mainly produced by the decomposition of organic matter in the absence of oxygen. It generally contains methane along with carbon dioxide and small amounts of other gases.
Key Points
- Methane is the major combustible component of biogas.
- Biogas is produced from organic matter.
- Biogas is formed in the absence of oxygen.
- Methane can be burned to produce energy.
- Carbon dioxide is another major component of biogas.
Real-Life Example: Biogas produced from animal dung and other organic waste can be used as a fuel for cooking.
19. Which gas is commonly used in the manufacture of fertilizers?
Answer: A. Ammonia
Explanation
Ammonia is an important compound used in the manufacture of many nitrogen-containing fertilizers. It contains nitrogen, which is an essential nutrient required for plant growth. Ammonia is used directly in some fertilizers and also serves as a starting material for producing other nitrogen fertilizers.
Key Points
- Ammonia has the chemical formula NH₃.
- It contains nitrogen.
- Nitrogen is an essential nutrient for plants.
- Ammonia is used to manufacture nitrogen fertilizers.
- It is an important industrial chemical.
Real-Life Example : Ammonia is used to produce fertilizers such as urea and ammonium compounds that supply nitrogen to crops.
20. Which statement about common chemical compounds is correct?
Answer: B. Washing soda is used for softening hard water
Explanation
Washing soda is sodium carbonate decahydrate, with the chemical formula Na₂CO₃·10H₂O, and it is commonly used for softening hard water. It reacts with dissolved calcium and magnesium salts and helps convert them into insoluble compounds that can be removed from the water. The other statements are incorrect because baking soda is not mainly used as a fuel, Plaster of Paris is used for casts and moulds, and bleaching powder is mainly used for bleaching and disinfection.
Key Points
- Washing soda is sodium carbonate decahydrate.
- Its chemical formula is Na₂CO₃·10H₂O.
- It is used for softening hard water.
- Baking soda has uses in baking and as an antacid.
- Plaster of Paris is used for casts and moulds.
- Bleaching powder is used for bleaching and disinfection.
Real-Life Example: Washing soda can be used to reduce the hardness of water by removing calcium and magnesium ions.
Important Points to Remember – Quick Revision
- Copper is a good conductor of electricity and is commonly used for making electrical wires.
- Aluminium is lightweight, malleable, corrosion-resistant, and a good conductor of heat. It is used for foil and utensils.
- Graphite is an allotrope of carbon and is used in pencil leads.
- Chlorine is commonly used to disinfect drinking water.
- Nitrogen is an essential nutrient for plants and is an important component of many fertilizers.
- Baking soda is sodium hydrogen carbonate, with the chemical formula NaHCO₃.
- Washing soda is sodium carbonate decahydrate, with the chemical formula Na₂CO₃·10H₂O.
- Washing soda is used for softening hard water and removing permanent hardness.
- Bleaching powder is commonly known as calcium oxychloride and is used for bleaching and disinfection.
- Plaster of Paris is calcium sulphate hemihydrate, with the chemical formula CaSO₄·½H₂O.
- Plaster of Paris hardens when mixed with water and is used for making casts for fractured bones.
- Vinegar commonly contains acetic acid, also known as ethanoic acid, with the formula CH₃COOH.
- Sodium hydrogen carbonate can be used as an antacid because it helps neutralize excess stomach acid.
- Carbon dioxide is produced in soda-acid fire extinguishers and does not support combustion.
- Quicklime is calcium oxide (CaO).
- Slaked lime is calcium hydroxide [Ca(OH)₂].
- Quicklime reacts with water to form slaked lime.
- Methane is the major combustible component of biogas.
- Ammonia (NH₃) is an important starting material for manufacturing nitrogen fertilizers.
Quick Memory Links
Baking soda → NaHCO₃
Washing soda → Na₂CO₃·10H₂O
Bleaching powder → Calcium oxychloride
Plaster of Paris → CaSO₄·½H₂O
Vinegar → Acetic acid → CH₃COOH
Quicklime → CaO
Slaked lime → Ca(OH)₂
Biogas → Methane
Fertilizers → Nitrogen / Ammonia
Drinking water disinfection → Chlorine
Further Reference For Test 5 “Important Elements and Compounds in Everyday Life”
Learners can explore the related study materials on Elements and Compounds to strengthen their understanding of important Chemistry concepts, students can refer to the NCERT Chemistry textbook chapter “Classification of Elements and Periodicity in Properties.” Reviewing these resources along with the quiz can help TNPSC aspirants revise key facts, chemical names, formulas, properties, and everyday applications more effectively.
