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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

What is the correct order of the processes in which hydrogen is removed from a substance and then added to a substance?Under which condition will iron rust the most?Painting and oiling prevent rusting based on which common principle?A student places an iron nail in a blue copper sulphate solution. After some time, a reddish-brown coating appears on the nail and the solution turns light green. What type of reaction is this?Why does oily food kept in warm, open air spoil quickly?A student states that the reaction \(2\mathrm{Mg}+\mathrm{O}_2\rightarrow2\mathrm{MgO}\) is not a displacement reaction because no element replaces another element from a compound. The student is correct because this reaction is which type of reaction?When a zinc strip is placed in a blue copper sulphate solution, which observation indicates a displacement reaction?In the reaction \(2\mathrm{FeCl_3} + \mathrm{SnCl_2} \rightarrow 2\mathrm{FeCl_2} + \mathrm{SnCl_4}\), which substance is the reducing agent?When an iron nail is placed in a blue copper sulphate solution, the solution turns green and a reddish-brown coating forms on the nail. What type of reaction is this?A student writes the reaction on placing an iron nail in aqueous copper sulfate solution as: \(2Fe + 3CuSO_4 \rightarrow Fe_2(SO_4)_3 + 3Cu\). What correction is required in the equation?In the thermite reaction \(Fe_2O_3 + 2Al \rightarrow Al_2O_3 + 2Fe\), which substance is reduced?In an experiment, copper powder forms black CuO when heated in air. When H2 is passed over it on heating, reddish-brown copper is obtained again. Which is the correct explanation of these changes?How is chewing food different from digesting it?Which statement identifies a reaction as a displacement reaction?Why should a chemical reaction not be confirmed carelessly from colour change alone?If gas evolves in an unknown reaction but colour does not change what is the most careful conclusion?A student writes the rusting reaction as \(Fe + H_2O \to Fe_2O_3 + H_2\). What is the most fundamental error in this statement?What is the correct difference between the symbols (aq) and (l) in a chemical equation?Which of the following is a chemical change but not a precipitation reaction?Which of the following is a decomposition reaction but not an electrolytic decomposition reaction?