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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

When bubbles are observed in a reaction mixture, what do they most commonly indicate?If a container becomes cold during a reaction, what can it indicate?In a chemical reaction, both heat and light are released. What type of reaction is it?Why is an upward arrow associated with gas in a chemical equation?A student places a clean iron nail in blue copper sulfate solution. Which observation confirms that a displacement reaction has occurred?What is the reaction called in which a more reactive metal displaces a less reactive metal from its salt solution?After converting a word equation into a chemical equation, what is the next main task?When is the law of conservation of mass correctly applied in a chemical equation?Why should a colour change alone not be considered conclusive evidence of a chemical reaction?If only the shape of a substance changes in a process and no new substance is formed, what type of change is it called?Why is digestion of food considered a chemical reaction?What is the correct reason for calling respiration an exothermic chemical reaction?Why is photosynthesis considered an energy-absorbing (endothermic) process?Which of the following reactions is not a displacement reaction?Which of the following reactions is both a combination reaction and an exothermic reaction?A student placed an iron nail in a blue copper sulphate solution. After some time, a reddish-brown coating formed on the nail and the solution began to turn green. What type of reaction is this?If a packaged food item contains a large amount of oil or fat, which method is most suitable to prevent rancidity?In an unknown reaction, a white solid forms and does not dissolve in water. What is the most suitable identification?In a closed system, the total mass before and after a reaction remains the same, but the properties of the substances change. What is the correct conclusion?When an iron nail is placed in a blue copper sulphate solution, what is the main reason the solution turns green?