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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 of the following equations represents a displacement reaction in which a more reactive metal displaces a less reactive metal from its aqueous salt solution?When an iron nail is placed in blue copper sulphate solution, the solution turns green and a reddish-brown coating forms on the nail. What type of reaction is this?A student places a zinc strip in a blue copper sulphate solution and claims that no chemical reaction has occurred. Which observation would prove the student's conclusion wrong?Which chemical process do antioxidants slow down in food?Which statement about oxidation and reduction is correct in the given equation? \(2\mathrm{FeCl_3} + \mathrm{SnCl_2} \rightarrow 2\mathrm{FeCl_2} + \mathrm{SnCl_4}\)A student classified the reaction \(2AgCl \xrightarrow{\text{sunlight}} 2Ag + Cl_2\) as a displacement reaction. What is its correct classification?If heat is shown on the reactant side of a chemical equation and one compound breaks down to form two or more products, what is the correct classification of the reaction?Which of the following equations is a correct example of a precipitation reaction?A student calls the reaction \(2AgCl(s) \xrightarrow{\text{sunlight}} 2Ag(s)+Cl_2(g)\) a displacement reaction because chlorine is released. What is the best correction of the student's error?What is the correct difference between the symbols q] and ] in a chemical equation?In which of the following reactions do oxidation and reduction occur simultaneously?In a closed container, a chemical reaction produces a gas and the temperature rises, but no matter escapes. What is the correct conclusion about the total mass of the container and its contents before and after the reaction?After a reaction in an open container, the measured mass appears lower because a gas produced has escaped. What is the correct scientific explanation?What is the deepest reason for keeping atoms of all elements equal on both sides of a balanced chemical equation?While balancing a chemical equation, why should the subscripts in chemical formulae not be changed?If iron atoms are equal but oxygen atoms are not equal in an equation, what is the equation?How many atoms are present in total in two water molecules?What will be the ratio of magnesium atoms to oxygen atoms in four formula units of magnesium oxide?Why is a magnesium ribbon cleaned by rubbing it with sandpaper before burning?Why is burning of magnesium both a combination reaction and an oxidation reaction?