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Subjects

Science

Chemical Reactions and Equations

रासायनिक अभिक्रियाएँ और समीकरण

In Class 10 Science, under the chapter Chemical Substances – Nature and Behaviour, this topic introduces chemical reactions as changes that form new substances. Students learn to identify reactants and products, represent reactions through word and chemical equations, and write balanced equations using correct chemical formulae while following the law of conservation of mass.

Practice questions

In a chemical reaction, oxygen is removed from substance A and the same oxygen is added to substance B. What is the most appropriate classification of this reaction?Which pair shows oxidation first and reduction second?Which of the following equations represents a double displacement reaction that forms a precipitate?Which of the following reactions is not an oxidation-reduction (redox) reaction?A student states that the reaction \(\mathrm{AgNO_3(aq)+NaCl(aq)\rightarrow AgCl(s)+NaNO_3(aq)}\) is both a precipitation reaction and a redox reaction. What is the correct evaluation of this statement?Why does exposed iron remain protected from rusting for some time even when the zinc coating in galvanisation is scratched?What is the main chemical cause of rancidity in oily food?Why will rancidity increase quickly in ghee kept in a warm open place?During electrolysis of acidified water, 15 mL of oxygen is collected at the anode. A student says that 15 mL of hydrogen will also be produced at the cathode because water contains both H and O. What is the correct correction to the student's statement?What common effect do antioxidants and airtight packaging have?If a container becomes very cold during a reaction, what is the most suitable explanation of the energy change?If heat is written along with the products in a chemical equation and light is also emitted during the reaction, what is the nature of the reaction?When a single compound breaks down into two or more simpler products on heating, what type of reaction is it?Why are both combustion and respiration considered exothermic processes?When a clean iron nail is placed in a blue \(CuSO_4\) solution, a reddish-brown coating forms on the nail. Which conclusion correctly explains this change?On what basis are chewing food and digesting it different?On what basis can the formation of curd from milk and the formation of ice from water be differentiated?In which situation should a colour change not be considered evidence of a chemical reaction?If gas evolves in an unknown reaction but colour does not change what will be the most careful conclusion?In a chemical equation, what do a downward arrow \(\downarrow\) and an upward arrow \(\uparrow\) written with products respectively indicate?