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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

Which fact should be considered while identifying a similarity between respiration and combustion?What does writing sunlight above the arrow in the following photosynthesis equation indicate? \(6CO_2 + 6H_2O \xrightarrow{\text{sunlight}} C_6H_{12}O_6 + 6O_2\)Why is digestion of food a chemical change, whereas chewing food is mainly a physical change?When an iron nail is kept in a blue copper sulphate solution for some time, the solution turns light green and a reddish-brown coating forms on the nail. Which is the correct explanation for this observation?Why should a final conclusion about a chemical reaction not be drawn from colour change alone?In an unknown chemical reaction, a gas was evolved and the container became cold. Which conclusion is the most cautious?A product written with a downward arrow in a chemical equation will have which property?If an upward arrow ↑ is written after a product in a chemical equation, which observation does it indicate?Which of the following correctly matches a state symbol with the state of a substance?Which statement correctly describes the difference between a skeletal chemical equation and a balanced chemical equation?Which change is the clearest indication that a chemical reaction has occurred?Which of the following reaction is both a combination reaction and an oxidation-reduction reaction?When an iron nail is placed in a blue copper sulphate solution, which observation identifies that a displacement reaction has occurred?In which of the following reactions does one part of the same reactant undergo oxidation while another part undergoes reduction?Which of the following observations most strongly indicates that an unknown reaction is a precipitation reaction?In which condition can conservation of mass be checked most correctly?In a closed container, 12 g of reactants completely undergo a reaction to form products, and no substance leaves the container. What will be the total mass of the products?While balancing a chemical equation, if a student changes a subscript in the formula of water, \(\mathrm{H_2O}\), what mistake has been made?In the balanced chemical equation for the formation of water, if there are 2 water molecules on the product side, how many oxygen molecules 0( 0 ext{O}_2 0) 0 are required on the reactant side?In the balanced combustion reaction of magnesium, if \(2\mathrm{MgO}\) is written on the product side, how many magnesium atoms must be on the reactant side?