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Q1: why respiration is called an exothermic reaction ? give example. Ans: in the respiration ,heat is released. So respiration is called an exothermic reaction. C6 H2 O6 H6o2 = 6Co2 + 6H20+ Heat. Q2: Decomposition reactions are called  of opposite of combination reaction . Why? Ans : because combination reaction two reactants combine to form one but in decomposition reactant break down into two. So that's why they are opposite of each other. Q3: which gas is produced during the decomposition of baking soda? Ans: carbon dioxide. Q4: what is chemical formula of common salt ? Ans: NAcl. Q5: give one example in which decomposition reaction is carried out by (A) electricity Ans: H20 electricity H2 + 02. (B) Heat Ans: Caco3 heat Ca0 +C02. Q6: what is thermal decomposition reactions? Ans: the decomposition reaction which state place in the presence of heat is called thermal decomposition reaction. Thermal decomposition reaction for example Caco3 heat Ca0 + C02. Q7: what is photo decomposi...

Chapter- Chemical Effect of Electric Current Part- A   Q1. What is an electdt ftrode? Ans.  An electrode is a conductor which is in contact with the electrolyte.   Q2. What is an ion? Ans.  The atom which becomes charged by losing or gaining one or more electrons is called an ion. Q3. Mercury is a liquid that conducts electricity, which constitutes a current through it? Ans.  In mercury, a current is constituted by the flow of free electrons. Q4. Why is an acid or an ionic salt added to water in the electrolysis of water?  Ans.  Because the ions of the ionic compound will increase the conductivity of water. Q5. A metal is released in the electrolysis is of salt at what electrode will it be deposited? Ans.  In the electrolysis of salt, all the metals are deposited at the cathode (negative terminal). Part- B Q1. Why are metals good conductors of electricity? Ans.  Some of the electrons in the metals are not tightl...

PART- A Q1: what do you mean by polluted air or water? Ans: if your water contains some substances that are harmful for us and our environment, then that air or water is said to polluted air or water. Q2: mention any three observation that indicate that a given sample of water is polluted? Ans: 1   its colour is dirty. 2 It tastes bad. 3 It is smells bad. 4 Oral oil grease is float in . Q3: what is chemical  pollution of water? Ans: if harmful chemicals mix with water bodies , then it cause chemical pollution of water. Q4: name the six chemical pollutants  of water. Ans: 1   oil and grease  2  Mineral acids 3  Pesticides and fertilizers 4  Metals and their compounds 5  Synthetic chemicals 6  Phosphate  from detergents. Q5: name four water- borne  diseases? Ans: typhoid Cholera Dysentery Hepatitis. Q6: what do you mean by portable water? Ans: the water which is good for drinking is called portable water. Q7 : how is ac...

PART - A Q1: what are non - renewable resources? Give two examples. Ans : the resources which cannot renewed by natural processes are called non - renewable resources For eg. Coal, petroleum and natural gas.   Q2: why is it said that plantations cannot make up for loss of primary forests? Ans: because man made forest Cannot fully complete the loss of primary forests. man made forest do not have many types of organisms that primary forests have. Q3: what are natural causes of deforestation? Ans: 1.  Droughts 2. Floods 3. Storms 4. Forest fire Q4: mention some human activities that cause deforestation? Ans: 1   production   of paper  2  Shifting cultivation 3  Making of furnitures 4  Making of factories 5  Making of roadways Q5: how do forest protect the soil? Ans: the cover of leaves protect the soil from the direct contact of rain and the root keep the soil in place. Q6: mention the consequences of deforestation. Ans: it leads to 1 Soil erosi...