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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 the balanced chemical equation for the formation of water, \(2\mathrm{H_2} + \mathrm{O_2} \rightarrow 2\mathrm{H_2O}\), what is the ratio of hydrogen molecules to oxygen molecules?Which pair of products is formed when calcium carbonate is heated?Which statement is correct about the reaction between calcium oxide and water?When a single compound breaks down into two or more simpler substances on heating, what is the reaction called?Why are silver chloride and silver bromide stored in dark-coloured bottles?During the electrolysis of water, which gas is obtained in a larger volume at the cathode?When an iron nail is placed in copper sulphate solution, which salt is mainly present in the green solution formed?Why does a reddish-brown layer form on an iron nail placed in copper sulphate solution?If metal A displaces metal B from its salt solution, what is the correct conclusion about metal A?What visible change occurs when aqueous solutions of sodium sulphate and barium chloride are mixed?Why is the reaction in which barium sulphate forms on mixing aqueous barium chloride and aqueous sodium sulphate called a precipitation reaction?Which of the following reactions is an example of both a double displacement reaction and a precipitation reaction?When hydrogen gas is passed over heated copper(II) oxide, the black copper(II) oxide changes into reddish-brown copper. Which statement correctly describes this reaction?Which of the following chemical equations represents a displacement reaction?A student places a clean iron nail in a blue copper sulphate solution. After some time, the solution turns green and a reddish-brown coating appears on the nail. What is the correct conclusion from this experiment?If hydrogen is added to a substance, which process is it generally called?If hydrogen is removed from a substance, which process is it generally considered to be?Why is rusting of iron considered a chemical change?Why does an iron object rust less when kept in an airtight, dry container?Why does the likelihood of rusting increase when the zinc coating in galvanisation is removed?