(e) Magnesium ribbon is burnt in oxygen. SURVEY . [NCT 2011] In Class 8 Science Chapter 10 we are going to discuss the period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence. Format, Eligibility Criteria, Documents Required, BIS Certificate | How to Get BIS Certified? After the electroplating of a spoon with silver, it was found that the anode has become thin. Question 4. 1. Exercise – I. Answer: X Your answer: For webquest or practice, print a copy of this quiz at the Chemistry: Chemical Reactions webquest print page. (ii) When carbon bums in oxygen to form a gaseous compound called carbon dioxide. Question 7. Answer: It causes rise in temperature. 26 Questions Show answers. [NCT 2011] Question 21. from potassium to gold. NIOS Certificate | Downloading Process, NIOS Certificate Criteria, NCL (Non-Creamy Layer Certificate) Certificate | How to Apply? Fill in the blanks. Hydrogen gas is evolved, with an effervescence. Answer: Insulators : distilled water, milk. (d) semi-insulator Is air an insulator or conductor of electricity ? Concise Chemistry - Middle School for Class 8 ICSE Author: Namrata Publisher: Selina Publishers Language: . NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. Question 1. of silver chloride is formed. NCERT Solutions for Class 8 Science Chapter 14 – 3 Mark Questions and Answers. (a) combination reaction (b) decomposition reaction (c) displacement reaction (d) double decomposition reaction Answer: (a) Combination reaction: A reaction in which two or more substances combine to form a single substance is called combination reaction. 30 seconds . CuSO 4.5H 2 O (s) ⇋ CuSO 4(s) + 5H 2 O (g) (d) Displacement. Method : Question 2. Explain your answer. (c) A catalyst can either increases or decreases the rate of chemical reaction and some chemical reactions need a catalyst to change the rate of the reaction, in case it is too slow or too fast. How should LED be connected ? (b) Silver chloride from silver nitrate. Electrodes are the terminals through which current is passed into a liquid. Question 10 What is the role of the Ozone layer in our atmosphere? List the possible reasons. To her surprise she found that the compass needle showed deflection. Each man carries within himself his own mountain peak. APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 8 Chemistry Chapter 6 Chemical Reactions. Answer: Q. So the practice set of Chemical Equilibrium with Important Questions And Answers helps students of class 11 and also for students studying for various competitive exams. During electroplating, the silver metal from the anode is deposited on the cathode. The free copper gets deposited on the plate acting as cathode. Take another piece of wire and connect it to the other terminal of the battery (Fig. Deposits can be seen in containers uses for storing water. Decoration of articles by giving them a layer for e.g., silver plating on cutlery. Which of the following is a chemical property of water? (d) electroplating. (i) When nitrogen and oxygen together are heated to a temperature of about 3000°C, nitric oxide gas is formed. What is electrolysis ? Do you find any difference in any one of them? Question 14. He finds that the compass needle deflects more in the case of seawater. Classify the changes involved in the following processes as physical or chemical changes: Answer: ... Classify the following as a physical or chemical change: A reaction takes place, and the product is different than what you started with. In this activity, if the bulb does not glow, it means that either the connections of the circuit are loose or the bulb is fused or cells are used up. Distilled water does not have any salts dissolved in it, but rain water may have some impurities in it. Thus water which is free of salts are poor conductors while water with salts is a good conductor of electricity. Wood is cut c. Bread is baked d. Wire is bent 9. CBSE Class 7 Science Physical and Chemical Changes Worksheets with Answers for Chapter 6 in PDF format to download prepared by expert Science teachers from latest edition of CBSE(NCERT) books. You may also get distilled water from a medical store or a doctor or a nurse). Solution: Question 2. 14.4). (g) In the type of reaction called double decomposition reaction, ions two compounds exchange their positive and negative radicals ions respectively. 8. (b), Question 5. Why? Collect a few small plastic or rubber caps of discarded bottles and clean them. About this quiz: All the questions on this quiz are based on information that can be found at Chemistry: Chemical Bonding . Question 4. What do you observe when (a) Iron nail is kept in copper sulphate solution for sometime. Use plating artificial jewellery with gold. No, pure water doesn’t conduct electricity. Question 5. 20 Questions Show answers. Materials which allow electric current to flow through them are called conductors. (iii) both liquids are equally conducting. Combustion and Flame Class 8 Notes, Question Answers. What do you conclude this time? When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Electrolytes conduct current at a slow rate than metals. Answer: As water is a good conductor of electricity so it can cause electrocution. It causes fall in temperature. The questions provided in General Science -Solutions Books are prepared in accordance with Maharashtra, thus holding higher chances of appearing on Maharashtra question papers. Answer: (a) Any chemical change in matter which involves transformation into one or more substances with entirely different properties is called a chemical reaction. Solution: (b) If the soil is acidic it can be treated with base like quick lime, to make it neutral. When electric current is passed in water hydrogen ions (H+) move towards cathode and get collected over it. Q. (b) cathode (e) Ammonia from nitrogen. Chapter 10 - Reaching the Age of Adolescence. Question 5. Fe + CuSO4 → FeSO4 + Cu. What property stays the same during physical and chemical changes? Combustion and Flame Class 8 Notes, Question Answers. ... Chemical Change: Rate & Extent. a. Density b. About this quiz: All the questions on this quiz are based on information that can be found at Chemistry: Chemical Bonding . AB + C → CB + A e.g. (b), Question 3. [NCERT] Wrap copper wires around the metal caps of the carbon rods and join them to a battery (Fig. (c) What do you understand by a chemical bond ? In this page, we are providing Physical and Chemical Changes Class 7 Extra Questions and Answers Science Chapter 6 pdf download. [NCERT] Answer: It cannot be said for sure that liquid does not conduct electricity because : may be the cells are weak. Important questions and answers of Chapter 6 physical and chemical changes of class 7 science. The passage of an electric current through a solution causes ……………….. effects. Graphite. Question 9 Why is it always advised not to play with fireworks? A + B → AB e.g (i) When iron and sulphur are heated together, they combine to form iron sulphide. Answer: Question 7. The writing appears on the paper. This happens because the when current is passed, the K+ ions are attracted to the metal sheet. Clean copper plates with sand paper. We prefer not to do electroplating on iron used for bridges because it is very costly. Answer: (a) Catalyst: A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change during the reaction. The loss of copper from solution is cqmpensated and the process goes on. (b) The melting of glaciers by global warming. Answer: He finds that the compass needle deflects more in the case of seawater. Bring your tester over this cap and let the ends of the tester dip into lemon juice or vinegar as shown in Fig. Support your answer with one example for each of them. Access Answers of Science NCERT Class 8 Chapter 14 Chemical Effects of Electric Current. You can download the Selina Concise Chemistry ICSE Solutions for Class 8 with Free PDF download option. (b) A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change. What precautions should be observed when doing electroplating ? If not, what can we do to make it conducting ? Which of the following IS a clue that a chemical change has occurred? (c) Name three biochemical catalysts found in the human body. Gradually, a layer of copper builds up on the plate. In this activity the bulb glows which shows that lemon juice and vinegar both conducts electricity, hence they are good conductors of electricity. Multiple Choice Questions for Icse Class 8 Chemistry Chapter 2 Physical And Chemical Changes Fill in the blanks. In a chemical reaction, the chemicals one starts with are called the: A reagents B reacting chemicals C products: 8. Q. upon publication. So, whenever you feel any problem, just refer to the solution book. Format, Samples and Guidelines. Science Important Questions Class 7 are given below. Question 2. Question 10 What is the role of the Ozone layer in our atmosphere? Bridges and automobiles are prevented from rusting by plating them with zinc. Compact Fluorescent Lamps. Explain your answer. Question 14. Name the gases formed when electric current is passed in water containing a few drops of acid ? (a) Magnesium oxide from magnesium. 14.6. Question 11 Define (1) galvanization The liquid is a conductor and the circuit is also complete, but the bulb does not glow. Answer: All questions and answers from the Living Science Book of Class 7 Science Chapter 8 are provided here for you for free. These MCQ Questions on Conservation of Plants and Animals Class 8 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Answer: Record your observations in Table 14.1. The solutions are designed according to the syllabus prescribed by CBSE guidelines. He must climb it to reach to a fuller knowledge of himself. Changes Around Us Class 6 Extra Questions Very Short Answer Type. Question 2. Question 2. Chemical Effects of Electric Current Class 8 Extra Questions Short Answer Questions. Name one non-metal which a good conductor of electricity. (b) pole Here you can get Class 7 Important Questions Science based on NCERT Text book for Class VII. Your tester with two free ends of the wire is ready. 1-6) Read the extract given below and answer the following questions. 6.1 Rate of Reaction; 6.2 Reversibility & Equilibrium; 7. NCERT Extra Questions for Class 7 Science Chapter 6 Physical and Chemical Changes with Answers will help to score more marks in your CBSE Board Exams. Question 10. Question 12. Answer: Does pure water conduct electricity? Good conductors are those conductors that allow current to pass through them. Which is the most common application of chemical effect of current ? Thus food, stored in iron cans, is prevented from being spoilt due to iron by electroplating it by tin. There are specific disposal guidelines for environmental protection. Question 3. (a) What is a chemical reaction? Also, use our NCERT solutions for Class 8 Science Chapter 8 to understand the difference between a zygote and a foetus. Why ? Question 10. Chromium is used for electroplating because it has a shiny appearance, does not corrode and is scratch resistant. There is another summit. Answer: Question 11. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. If the tester is working, it can be used to test the materials, i.e., whether it is a conductor or non-conductor of electricity. Answer: Class 6 Science Chapter 6 Extra Questions and Answers Changes Around Us. Therefore, we can be electrocuted in case we touch appliances with wet hands. Fill in the blanks. Why the iron cans are electroplated with tin ? Question 18. (c) A chemical bond is the attractive force that holds the atoms of a molecule together, in a compound. Question 2. Science worksheets for class 7 CBSE includes worksheets on Physical and Chemical Changes as per NCERT syllabus. Tin is less reactive than iron. No, it is highly dangerous to carry out the electrical repairs outdoors during the heavy downpour. The two free ends of wire are connected to the material to be tested. By volume of hydrogen gas is twice the volume of oxygen gas. (b) Some chemical reactions can take place in the presence of light. In containers, water evaporates slowly. Question 3. The free copper gets drawn to the plate connected to the negative terminal of the battery and gets deposited on that plate. How can you make a tester for testing whether a given material is a conductor or an insulator ? 1. When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Answer: Answer: Electroplating. The thick rod of impure copper plate is to be attached to the positive terminal of the battery because when electric current is passed through the copper sulphate solution, it gets dissociated into copper and sulphate. (d) chemical energy into magnetic energy So, the deflection of the compass needle is more. Physical and Chemical Changes, CBSE Science Class 7 Chapter Wise Solved Q&A. A chemical reaction in which the direction of a chemical change can be reversed by changing the conditions under which the reaction is taking place is called a reversible reaction. H2SO4 → Zn SO4 + H2. Explain why they do this. How do the following help in bringing about a chemical change? (c) When a solution of silver nitrate is added to a solution of sodium chloride, white insoluble ppt. Join the free ends of the tester together fora moment. We cannot make the whole article from it because it is a very costly metal. Solution: (b) What happens during a chemical reaction ? Which of the following metal is not extracted by electrolysis? Can you explain the reason? Chemical Reactions and Equations Class 10 Important Questions Very Short Answer Type Question 1. AgNO3 (aq) + NaCl (aq) → AgCl (ppt) + NaNO3 (aq), (d) When ferrous sulphate solution is added to sodium hydroxide solution, a dirty green ppt. Question 12. (a) magnetic energy into chemical energy Answer: Bonds… The salts separate out and deposit on the sides of the container. (b) a few pieces of iron are dropped in a blue solution of copper sulphate? Questions and Answers 1. Answer: Answer: LEDs require very little energy and glow even if a small current is passing through the circuit. Question 2. Which example is a chemical change? Water freezes b. (c) Catalyst: A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change. The ease with which a metal in solution loses electron(s) and forms a positive ion decreases down the series, i.e. Rainwater is pure water which is an insulator but it gets mixed with air pollutants like sulphur dioxide and nitrogen oxides and form acidic solution, which is a good conductor of electricity. Add a few drops of lemon juice or dilute hydrochloric acid to distilled water in one cap. Give one example each of which illustrates the following characteristics of a chemical reaction: (a) evolution of a gas (b) change of colour (c) change in state Answer: (a) When Zinc reacts with dil. Selina Publishers Concise Chemistry for Class 8 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines. Question 8 . Practice MCQ Questions for Icse Class 8 Chemistry Chapter 2 Physical And Chemical Changes with Answers to improve your score in your Exams. Answer: Write the missing reactants and products and balance the equations. Paheli had heard that rainwater is as good as distilled water. (d) electro refining Magnesium ribbon burns with a dazzling flame in air (or oxygen) and changes to a white substance magnesium oxide. An example of a chemical property is reactivity. Or, the bulb is fused? In an acid is added to a temperature of about 3000°C, nitric oxide gas oxygen! 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Icse Solutions for selina Concise Chemistry for Class VII 2 O ( g ) in the used. What happens during a chemical change the sides of the tester together fora moment costly metal a shiny appearance does. Sulphuric acid to copper sulphate solution to which a good conductor of electricity so it can be by! Deposited on the sides of the compass needle showed deflection with tap water hydrogen when subjected to high produce... Because: Question 2 during preparation Chemistry Notes by experts molecules change a... The decomposition of hydrogen chloride.gas positive and negative radicals ions respectively are prevented from being due! Found that the ends are not more than 1 cm apart but at same! A person suffering from acidity is advised to practice and understand all the questions on Physical and changes... & answers on Physical and chemical changes as per ICSE board guidelines our ICSE Chemistry Class 8 Science Chapter chemical. 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