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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

If a white insoluble solid forms in a solution but the temperature does not change, what is the correct conclusion?If a colour change is observed in a process, can it be identified conclusively as a chemical reaction on this basis alone?Which option gives the correct meaning of upward and downward arrows in a chemical equation?In a chemical equation, in which situation is the symbol (aq) correctly used?Which option correctly states the position of reactants and products in a chemical equation?During an unknown process in a closed container, the properties of a substance changed, a new substance was formed, and the total mass remained unchanged. What is the most appropriate conclusion?Ten grams of calcium carbonate is heated in a closed container. If no gas escapes, what will be the total mass of the products?In an unbalanced equation, oxygen atoms are fewer on the right side. What is the most correct method during balancing?In the balanced reaction in which hydrogen and oxygen form water, if there are two water molecules on the product side, how many hydrogen molecules are required on the reactant side?In the burning reaction of magnesium, the coefficient of the oxygen molecule displaystyle \(\mathrm{O_2}\) is 1. What will be the coefficient of magnesium displaystyle \(\mathrm{Mg}\) in the balanced equation?When water is added to calcium oxide, calcium hydroxide is formed and a large amount of heat is released. What type of reaction is this?When calcium carbonate is heated, the gas produced turns limewater milky. Which gas is it?When lead nitrate is heated, a brown gas and oxygen are formed. What is the solid residue?Why is it incorrect to identify the brown fumes observed on heating lead nitrate as oxygen?When silver chloride is kept in sunlight, it turns grey. Which form of energy is mainly responsible for this change?Why is the use of silver bromide in photography possible?In the electrolysis of water, the volumes of gases collected at the cathode and anode are in the ratio 2:1. If the gas with the lower volume is oxygen, which gas has the higher volume?When an iron nail is dipped in a copper sulfate solution, which observation confirms a displacement reaction?When an iron nail is placed in copper sulphate solution, its mass may increase slightly. What is the most appropriate reason?When an iron nail is placed in a blue copper sulphate solution, the blue colour gradually fades because the concentration of which ion decreases?