I. Four alternatives are given to each of the following incomplete statement\/ question. Choose the right answer.<\/p>\n
Question 1.
\nBalancing of equations is based on
\na) Avogadro’s number
\nb) condition for a chemical reaction to take place
\nc) law of conservation of mass or matter.
\nAnswer:
\nc) law of conservation of mass or matter.<\/p>\n
Question 2. Question 3. Question 4. Question 5. II. Balance the following reactions.<\/p>\n 1. Cu + H2<\/sub>SO4<\/sub>\u00a0 \u2192 <\/span>CuSO4<\/sub>\u00a0+ SO2 <\/sub>+ H2<\/sub>O \u2191 III. Answer the following.<\/p>\n 1) Write any three differences between a physical change and chemical change. 2) Group the following into physical change and chemical change. Dissolving salt in H2<\/sub>O, Burning of a fuel, Rusting or iron, melting of an ice cube. Question 3. Question 4. Question 5. Question 6. Question 7. Question 8. IV. Given the scientific reason for the following<\/p>\n Question 1. Question 2. Question 3. Question 1. Question 2. Question 3. Answer:<\/p>\n Question 4. Question 5. Question 6. Question 7. Question 8. Question 9. Question 10. Question 11. Question 12. Question 13. Karnataka Board Class 8 Science Chapter 11 Chemical Reactions and their Types KSEEB Class 8 Science Chapter 11 Textual Questions & Answers I. Four alternatives are given to each of the following incomplete statement\/ question. Choose the right answer. Question 1. Balancing of equations is based on a) Avogadro’s number b) condition for a chemical …<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/4900"}],"collection":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/comments?post=4900"}],"version-history":[{"count":0,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/4900\/revisions"}],"wp:attachment":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/media?parent=4900"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/categories?post=4900"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/tags?post=4900"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nIdentify the balanced equation in the following.
\nSiO2 <\/sub>+ Mg \u2192 Si + MgO
\nSiO2<\/sub> + 2Mg \u2192 Si + 2MgO
\nSiO + Mg \u2192 Si + MgO2<\/sub>
\nSiO2<\/sub> + Mg \u2192 SiO + 2MgO
\nAnswer:
\nb) SiO2<\/sub> + 2Mg \u2192 Si + 2MgO<\/p>\n
\nCorrect statement about chemical displacement is.
\na) less reactive element displaces a more reactive element
\nb) a non-metal displaces more reactive non-metal
\nc)\u00a0 more reactive element displaces the less reactive element
\nd) evolution of heat when carbon is burnt in air
\nAnswer:
\nc) more reactive element displaces the less reactive element<\/p>\n
\nDissolving of sugar in water is not an example of a chemical reaction because
\na) there is no change in energy
\nb) sufficient heat is not produced
\nc) no new substance is formed
\nd) no gases are evolved.
\nAnswer:
\nc) no new substance is formed<\/p>\n
\nWhich of the following represents a combination of two compounds forming another compound?
\na) 2SO2<\/sub> + O3<\/span> \u2192 2SO3<\/span>
\nb) CaCO2 <\/sub>\u2192 CaCO +CO2<\/sub>
\nc) H2<\/span>O+ SO2<\/sub>\u2192 H2<\/span>SO3<\/span>
\nd) 2Na + 2H2<\/span>O \u2192 2NaOH + H2\u00a0<\/span>
\nAnswer:
\nc) H2<\/span>O + SO2<\/sub> \u2192 H2<\/span>SO3<\/span><\/p>\n
\n2. Fe + H2<\/sub>O \u2192 <\/span> Fe3<\/sub>O4<\/sub>\u00a0<\/span>+ H2<\/sub>
\n3. CH4<\/sub>\u00a0+ O2 <\/sub> \u2192 <\/span>CO2<\/sub>+ H2<\/sub>O
\nAnswer:
\n1. Cu + 2H2<\/sub>SO4<\/sub> \u2192 <\/span>CuSO4<\/sub>\u00a0+ SO2<\/sub>+ 2H2<\/sub>O
\n2. 3Fe + 4H2<\/sub>O \u2192 <\/span>Fe3<\/sub>O4<\/sub>\u00a0<\/span>+ 4H2<\/sub>
\n3. CH4 + 2O2<\/sub> \u2192\u00a0 <\/span>CO2<\/sub> + 2H2<\/sub>O<\/p>\n
\nAnswer:<\/p>\n\n\n
\n Physical change<\/td>\n Chemical change<\/td>\n<\/tr>\n \n 1) Temporary and easily reversible<\/td>\n Permanent and sometimes reversible<\/td>\n<\/tr>\n \n 2) No new substance is formed.<\/td>\n New substance is formed.<\/td>\n<\/tr>\n \n 3) No change in mass<\/td>\n Weight of the substance is altered.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\nAnswer:<\/p>\n\n\n
\n Physical change<\/td>\n Chemical change<\/td>\n<\/tr>\n \n 1) Dissolving salt in H2<\/sub>O<\/td>\n Burning of a fuel<\/td>\n<\/tr>\n \n 2) Melting of ice cube<\/td>\n Rusting of iron<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
\nMention one example each for the different types of chemical reactions.
\nAnswer:
\nThe different types of chemical reactions are
\n1. Chemical combination
\nEx : S + O2 <\/sub>\u2192 <\/span>SO2<\/sub>
\n2. Chemical decomposition
\nEx: 2KMnO4 <\/sub>\u2192 <\/span>K2<\/sub>MnO4<\/sub>+ MnO2<\/sub> + O2
\n<\/sub>3. Chemical displacement
\nEx : Zn + H2<\/sub>SO4 <\/sub>\u2192 <\/span>\u00a0ZnSO2<\/sub> + H2\u00a0<\/sub>\u2191
\n4. Chemical double decomposition
\nEx : MgSO4<\/sub> \u00a0+ Na2<\/sub>CO3 <\/sub>\u00a0\u2192\u00a0 <\/span>MgCO3<\/sub> + Na2<\/sub>CO4<\/sub><\/p>\n
\nClassify the following into chemical combination, decomposition, displacement and double displacement reaction.
\n1. CaCO3\u00a0 <\/sub>\u2192 <\/span> CaO + CO2<\/sub> \u2191
\n<\/sub>2. 2AgNO3<\/sub>+ Cu \u2192 <\/span> Cu(NO3<\/sub>)2<\/sub> + 2Ag \u2193
\n3. 2SO2<\/sub>+ O2<\/sub> \u2192 <\/span>2SO3 <\/sub>\u2191
\n<\/sub>4. NaCl + AgNO3<\/sub> \u2192\u00a0 <\/span>AgCl +NaNO3<\/sub>
\nAnswer:<\/p>\n\n
\nWrite the advantages of writing a chemical equation using formulas and symbols.
\nAnswer:
\nThe advantages for writing a chemical equation using formula and symbols are<\/p>\n\n
\nDuring winter so many plant leaves fall on earth But it will not cause pollution plastic papers which arc strew on the earth cause pollution. Name the type of chemical reaction associated with this observation.
\nAnswer:
\nThe type of reaction observed here is chemical decomposition the leaves that fall on the earth during the winter season get decomposed the carbohydrates present in the leaves are decomposed into simple sugar which can be absorbed by the plants whereas plastic is not decomposed so it adds to pollution.<\/p>\n
\nLPG gas contains butane. Its molecular formula is C4<\/sub>H10<\/sub>. Name the possible products when it undergoes complete combustion.
\nAnswer:
\nCombustion is an oxidation reaction 2C4<\/sub>H10<\/sub> + 16O2\u00a0 <\/sub>\u2192 <\/span>16O2\u00a0 <\/sub>8CO2<\/sub> + 10H2<\/sub>O
\nCO2<\/sub> and H2<\/sub>O are the products formed when C4<\/sub>H10<\/sub> undergoes complete combustion.<\/p>\n
\nSuggest some measures to avoid rancidity of oils.
\nAnswer:
\nSome of the measures to avoid rancidity of oils are as follows<\/p>\n\n
\n
\nIron displaces copper from copper sulfate but copper cannot displace iron.
\nAnswer:
\nIron displaces copper from copper sulfate but copper cannot displace iron. Iron is more reactive than copper. Hence the more reactive element iron displaces the less reactive element copper.<\/p>\n
\nRespiration is an exothermic reaction.
\nAnswer:
\nDuring respiration, glucose combines with the oxygen in the cells of the body and releases energy. Hence respiration is an exothermic reaction.<\/p>\n
\nUse of plastic must be avoided or minimized.
\nAnswer:
\nPlastic must be avoided or minimized because plastic pollutes soil and water and kill thousands of marine mammals yearly. Conventional plastics like polyethylene, polypropylene, polystyrene, PVC, PET or non-biodegradable.<\/p>\nKSEEB Class 8 Science Chapter 11 Additional Questions & Answers<\/h3>\n
\nGive an example of a complex chemical reaction.
\nAnswer:
\n\u2018Photosynthesis\u2019 is a complex chemical reaction<\/p>\n
\nGive an example of simple chemical reactions.
\nAnswer:
\nRusting of iron and combustion of fuels are simply chemical reactions.<\/p>\n
\nClassify the’following into chemical and physical changes.<\/p>\n\n
\n
\nWhat is the cause of the chemical reaction?
\nAnswer:
\nA chemical reaction means a rearrangement of the configuration to acquire the electronic configuration of the nearest stable or noble gas by transferring or sharing the electrons.<\/p>\n
\nWhat is a valence electron?
\nAnswer:
\nThe electrons which take part in chemical reactions are called valence electrons.<\/p>\n
\nWhat is the balancing of the equation?
\nAnswer:
\nThe practice of equalizing the number of atoms of elements on the left-hand side to the corresponding atoms on the right hand side is called balancing of the equation.<\/p>\n
\nState the law of conservation of matter or mass.
\nAnswer:
\nLaw of conservation of matter or mass states that matter can neither be created nor destroyed.<\/p>\n
\nMention the types of chemical reactions.
\nAnswer:
\nThe chemical reactions are mainly of the following types based on the nature of reactants and products.<\/p>\n\n
\nWhat is meant by chemical combination? Give an example.
\nAnswer:
\nChemical combination is a reaction in which two or more elements or compounds combine to form a new product.
\nEx:
\n1. N2 <\/sub>+ H2 <\/sub>\u2192 2NH3
\n<\/sub>2. S + O2<\/sub> \u2192 SO2<\/sub><\/p>\n
\nWhat do you mean by Haber\u2019s process
\nAnswer:
\nHaber designed the technology of synthesizing ammonia. He won a Nobel prize in chemistry for this contribution. In this process, Nitrogen and Hydrogen are subjected to high pressure at a temperature of about 500\u00b0C in the presence of a catalyst.<\/p>\n
\nWhat is meant by chemical decomposition? Give an example.
\nAnswer:
\nChemical decomposition is a reaction in which a compound breaks up into two or more new substances.
\nEx :
\n1. 2HgO \u2192 2Hg + O2<\/sub> \u2191
\n2. 2KMnO4 <\/sub>\u2192\u00a0 K2<\/sub>MnO4<\/sub> + MnO2<\/sub> + O2<\/sub><\/p>\n
\nWhat is chemical displacement? Give an example.
\nAnswer:
\nChemical displacement is a reaction in which more reactive elements displaces the less reactive elements from their compounds.
\nEx:
\n(1) CuSO4 <\/sub>+ Fe \u2192\u00a0 FeSO4<\/sub>+ Cu \u2193
\n(2) Cl2<\/sub>+ 2Kl \u2192\u00a0 2KCl +l2\u00a0\u00a0<\/sub>\u2193<\/p>\n
\nWhat is meant by chemical double decomposition? Give an example.
\nAnswer:
\nChemical double decomposition is a reaction in which there is a mutual exchange of metallic and non-metal lie parts. Such reactions are also called a double chemical exchange.
\nCaCl2 <\/sub>+ Na2<\/sub>CO3 <\/sub>\u2192\u00a0 CaCO3<\/sub> \u2193 + 2NaCl
\nMgSO4<\/sub> + Na2<\/sub>CO3<\/sub> \u2192\u00a0 MgCO3 <\/sub>\u2193 \u00a0<\/sub>+ Na2<\/sub>SO4<\/sub><\/p>\n KSEEB Solutions for Class 8 Science<\/a><\/h4>\n","protected":false},"excerpt":{"rendered":"