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4.   Answer the Following :  Question: (a) What do you understand by the term fuel?  Check the Correct Answer 🌟 Sample Ideal Answer: Answer (a):  A material that burns to release a large amount of heat and light energy. ----------------------------------------------------- Question: (b) Name any four common household fuels.  ⚠️ Write your thoughts first! ⚠️ Reveal the Correct Answer 🌟 Sample Ideal Answer: Answer: LPG, Kerosene, Wood, and Biogas. ------------------------------------------------------------------ Question: (c) Name the products formed during the combustion of a fuel. ⚠️ Please type your scientific explanation first! ⚠️ Check My Answer 🌟 Ideal Answer: Answer: Carbon dioxide, water vapour, and heat energy.

3. Question: Briefly describe how you will prove the presence of following in air:  (a) water vapour  (b) carbon dioxide ⚠️ Think and type first! ⚠️ Check the Correct Answer 🌟 Sample Ideal Answer: Answer (a): By placing ice in a glass tumbler; droplets appearing on the outside prove water vapour is present. Answer (b):  By passing air through limewater; it turns milky, proving carbon dioxide is present.

2. Answer the following: (a)  Name a major constituent of air which does not take part in the process of combustion. (b)  Name a constituent of air which is essential for combustion and respiration. (c)  Name the constituent of air which is essential for photosynthesis. ⚠️ Think and type first! ⚠️ Check the Correct Answer 🌟 Sample Ideal Answer: (a) Nitrogen  (It is an inert gas that does not support burning). (b) Oxygen  (Essential for oxidation in both fire and living cells). (c) Carbon dioxide  (Used by plants to produce food).

🌬️ Challenge 5: The Breath of Earth 1. Question: Answer the following questions: Question: Name four important constituents of air and state their appropriate percentage in composition. ⚠️ Think and type first! ⚠️ Check the Correct Answer 🌟 Sample Ideal Answer: Nitrogen - (78.03%), Oxygen - (20.9%), Carbon dioxide - (0.03%), Other gases - (0.94%) - Noble gases like Argon, Helium, Neon, Krypton, Xenon, Radon and Water Vapour and Ozone.

Exercise 5.1: Air and Atmosphere (Q&A) Section A: Fill in the Blanks Question: Fill in the blank spaces by choosing the correct words in brackets. Question: Oxygen is necessary for respiration and ___________ [photosynthesis/combustion] Answer: combustion Question: The envelope of air which surrounds the earth is known as ___________ [exosphere/atmosphere] Answer: atmosphere Question: The life supporting constituent of air is ___________ [nitrogen/oxygen] Answer: oxygen Question: When products of combustion are passed through anhydrous copper sulphate, it turns ___________ [yellow/blue] Answer: blue Question: When clear limewater is exposed to air for some time it turns ___________ [milky/pink] Answer: milky Section B: Correct the Statements Statements given below are incorrect. Write the correct statements: Question: The products of the combustion of a fuel are nitrogen and water vapour. Correction:  The products of the combustion of a fuel are carbon dioxide and water va...

EXERCISE 5.1: SECTION A - FILL IN THE SPACES BY CHOOSING THE CORRECT WORDS IN THE BRACKETS. Select the correct word for each observation. 1. Oxygen is necessary for respiration and ________. -- Select Answer -- Photosynthesis Combustion 2. The envelope of air surrounding the earth is the ________. -- Select Answer -- Exosphere Atmosphere 3. The life supporting constituent of air is ________. -- Select Answer -- Nitrogen Oxygen 4. Products of combustion turn anhydrous copper sulphate ________. -- Select Answer -- Yellow Blue 5. Clear limewater exposed to air for some time turns ________. -- Select Answer -- Milky ...

🔬 Air & Atmosphere Lab Choose the correct constituent or property! 1. Oxygen is necessary for respiration and ________. Photosynthesis Combustion 2. The envelope of air surrounding the earth is the ________. Exosphere Atmosphere 3. The life supporting constituent of air is ________. Nitrogen Oxygen 4. On contact with combustion products, anhydrous copper sulphate turns ________. Yellow Blue 5. When clear limewater is exposed to air, it turns ________. Milky Pink Calculating Score... Reset Worksheet

Here is a concise Study Guide & Cheat Sheet that summarizes the chemical reactions, tests, and key concepts from Exercise 5.1. This is perfect for students to keep in their notebooks for quick revision. 🚀 Air and Atmosphere: The "Cheat Sheet" 1. The Big Two: Air Composition Air is a mixture of gases. The two most abundant are: Nitrogen ( $N_2$ ): 78% (The "Inert" gas – it doesn't help things burn). Oxygen ( $O_2$ ): 21% (The "Supporter" – essential for life and fire). 2. The Science of Combustion (Burning) Combustion is a chemical reaction between a fuel and oxygen that produces energy. The Combustion Formula: $$\text{Fuel} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water Vapour} + \text{Heat} + \text{Light}$$ 3. Lab Tests: Identifying Gases How do we know which gas is which? We use these chemical "indicators": Gas to Test Testing Material Result Carbon Dioxide ( $CO_2$ ) Fresh Limewater Turns Milky Water Vapour ( $H...

  Here are more Quick Exam Tips tailored specifically from the investigations and theoretical pages of your chapter. These are designed to help students handle common "Why?" and "How?" questions in their chemistry exams. 🧪 Practical Investigation Tips 💡 Quick Tip for the Exam: If a question asks why a candle goes out when covered with a jar, the answer is always: "The supply of oxygen is cut off, and oxygen is a necessary supporter of combustion." 💡 Quick Tip: The "Milky" Result If a question asks what happens when air is bubbled through limewater, the answer is: "The limewater turns milky due to the formation of insoluble calcium carbonate, proving the presence of carbon dioxide." 💡 Quick Tip: The Water Vapour Proof If asked how to prove the presence of water vapour in the air without chemicals, the answer is: "Place ice in a glass; droplets form on the outer surface because water vapour in the air condenses upon touching the...

📊 Master Summary Table: Air and its Constituents Constituent Percentage (Approx.) Key Function / Use Identification Test Nitrogen ( $N_2$ ) 78.03% Dilutes oxygen; used to preserve food and make fertilizers. Does not support combustion; no reaction with limewater. Oxygen ( $O_2$ ) 20.9% Essential for respiration and combustion. A glowing splint bursts into flame. Noble Gases (e.g., Argon) 0.94% Used in advertising signs and electric bulbs (Inert). Chemically inactive; does not react with common reagents. Carbon Dioxide ( $CO_2$ ) 0.03% Essential for photosynthesis; used in fire extinguishers. Turns freshly prepared limewater milky . Water Vapour ( $H_2O$ ) Variable Influences weather/climate; prevents drying of tissues. Turns white anhydrous copper sulphate blue . Dust & Smoke Variable Provides nuclei for water vapour to condense into rain. Observed as tiny moving particles in a beam of light. ⚡ Quick Revision: The "Big Three" Experiments 1. The Candle and Jar Experiment...