Chemical Reactions and Precipitation Quiz
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Questions and Answers

What is the purpose of adding dilute sulphuric acid to the water in the mug?

  • To change the color of the electrolyte
  • To enhance the conductivity of water (correct)
  • To prevent the formation of bubbles
  • To generate heat for the reaction

    • What are the bubbles observed at both electrodes during electrolysis made of?

  • Nitrogen gas
  • Oxygen and hydrogen gases (correct)
  • Carbon dioxide gas
  • Chlorine gas

    • How can you determine which gas is collected in each test tube after electrolysis?

  • By measuring the volume of gas collected in each test tube
  • By igniting a burning candle near the mouth of the test tubes (correct)
  • By tasting each gas to identify them
  • By letting the gases mix and observing the color change

    • In the process of balancing the chemical equation discussed, which element was left unbalanced until Step V?

    <p>Iron</p> Signup and view all the answers

    What color change does silver chloride undergo when exposed to sunlight?

    <p>It turns grey</p> Signup and view all the answers

    What is the significance of the hit-and-trial method in balancing chemical equations?

    <p>It involves using the smallest whole numbers</p> Signup and view all the answers

    What are the products formed when silver chloride decomposes in sunlight?

    <p>Silver and chlorine gas</p> Signup and view all the answers

    How many molecules of hydrogen were initially present in the reactants before balancing the equation?

    <p>8</p> Signup and view all the answers

    Which chemical equation represents the decomposition of silver chloride into silver and chlorine gas in sunlight?

    <p>$2AgCl(s) ightarrow 2Ag(s) + Cl2(g)$</p> Signup and view all the answers

    What does the number 4 represent in the balanced chemical equation 3Fe + 4H2O → Fe3O4 + 4H2?

    <p>Number of water molecules</p> Signup and view all the answers

    How many atoms of iron are present in the products after balancing the equation?

    <p>3</p> Signup and view all the answers

    What information is NOT provided by a balanced chemical equation like 3Fe + 4H2O → Fe3O4 + 4H2?

    <p>Physical states of reactants and products</p> Signup and view all the answers

    What is the term used to describe the insoluble substance formed in a chemical reaction?

    <p>Precipitate</p> Signup and view all the answers

    In the reaction Na2SO4(aq) + BaCl2(aq) → BaSO4(s) + 2NaCl(aq), what is the role of BaSO4?

    <p>Precipitate</p> Signup and view all the answers

    What causes the formation of the white precipitate of BaSO4 in the reaction mentioned?

    <p>Reaction of SO4^2- and Ba^2+ ions</p> Signup and view all the answers

    What type of reactions involve an exchange of ions between the reactants?

    <p>Double displacement reactions</p> Signup and view all the answers

    In the context of oxidation and reduction, what is observed when copper powder is heated with oxygen?

    <p>Black coating of copper(II) oxide</p> Signup and view all the answers

    Why does black copper(II) oxide form when oxygen is added to copper?

    <p>Oxygen reacts with copper to form a black substance</p> Signup and view all the answers

    Which of the following statements about the reaction 2PbO(s) + C(s) → 2Pb(s) + CO2(g) is incorrect?

    <p>Carbon is getting oxidised.</p> Signup and view all the answers

    In the reaction Fe2O3 + 2Al → Al2O3 + 2Fe, what type of reaction is being exemplified?

    <p>Combination reaction.</p> Signup and view all the answers

    What occurs when dilute hydrochloric acid is added to iron fillings?

    <p>Hydrogen gas and iron chloride are produced.</p> Signup and view all the answers

    Why should chemical equations be balanced?

    <p>To conserve mass and atoms in a chemical reaction.</p> Signup and view all the answers

    Translate 'Hydrogen gas combines with nitrogen to form ammonia' into a balanced chemical equation.

    <p>3H2 + N2 → 2NH3</p> Signup and view all the answers

    Balance the chemical equation: NaOH + H2SO4 → Na2SO4 + H2O

    <p>NaOH + H2SO4 → Na2SO4 + 2H2O</p> Signup and view all the answers

    What is the purpose of applying paint on iron articles?

    <p>To prevent oxidation of iron</p> Signup and view all the answers

    Why are oil and fat containing food items flushed with nitrogen?

    <p>To prevent oxidation</p> Signup and view all the answers

    Which term describes the process of metal deteriorating due to chemical reactions with its surroundings?

    <p>Corrosion</p> Signup and view all the answers

    What happens when a shiny brown colored element is heated in air and turns black?

    <p>The element undergoes oxidation</p> Signup and view all the answers

    In the group activity described, which substance would likely lead to an exothermic reaction when added to water?

    <p>Fine iron fillings</p> Signup and view all the answers

    What is the purpose of adding nitrogen to oil and fat-containing food items?

    <p>To prevent rancidity</p> Signup and view all the answers

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