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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 difference between the aqueous symbol \((aq)\) and the liquid symbol \((l)\) in a chemical equation?Which statement correctly identifies oxidation and reduction in the reaction \(\mathrm{CuO + H_2 \rightarrow Cu + H_2O}\)?Which of the following reactions is both a displacement reaction and a redox reaction?In the reaction \(CuO + H_2 \rightarrow Cu + H_2O\), which substance is the reducing agent?In which situation will checking conservation of mass be most reliable?In the reaction CuO + H₂ → Cu + H₂O, which is the correct identification of oxidation and reduction?In a closed container, a total of 20 g of reactants undergo a reaction to form products, and any gas produced remains inside the container. What will be the total mass of the products?If a gas is produced during a chemical reaction, what precaution should be taken while verifying the law of conservation of mass?In the balanced chemical equation 2H₂ + O₂ → 2H₂O for the formation of water, how many hydrogen atoms are present in total on the product side?In the balanced equation for burning magnesium, \(2\mathrm{Mg}+\mathrm{O}_2\rightarrow2\mathrm{MgO}\), how many oxygen atoms are present on the product side?Why is it incorrect to change the subscripts in the formula of a compound while balancing a chemical equation?In the reaction of calcium oxide with water, only one product is formed and heat is released. What is the correct combined classification of this reaction?The gas evolved on heating calcium carbonate turns lime water milky. Which gaseous product does this confirm?Which solid product is formed on thermal decomposition of calcium carbonate?The brown gas on heating lead nitrate indicates the presence of which substance?Which is the correct pair of solid residue and brown gas formed on heating lead nitrate?Silver chloride turns grey in sunlight. This change is related to which energy and which product?What is the most suitable reason for storing silver bromide in a dark-coloured bottle?During the electrolysis of water, at the same temperature and pressure, if the volume of hydrogen gas obtained is 20 mL, what will be the volume of oxygen gas?A student heated calcium carbonate in an open test tube. The mass of the solid decreased after heating, so the student concluded that the law of conservation of mass is incorrect. What is the correct correction to this conclusion?