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ChemistryClass 10ICSE

The process of respiration is: (a) An oxidation reaction which is endothermic (b) A reduction reaction which is exothermic (c) A combination reaction which is endothermic An oxidation reaction which is exothermic

Option (d) is the answer. During digestion the food what we have taken breakdown and gives energy. If we are having carbohydrate content food items, it break downs to glucose and it combines with oxygen to give energy and thus addition of oxygen takes place and energy is also released

ChemistryClass 10ICSE

Consider the following equation of the chemical reaction of a metal M: 4M + 3O2→ 2M2O3 The equation represents: (a) Combination reaction as well as reduction reaction (b) Decomposition reaction as well as oxidation reaction (c) Oxidation reaction as well as displacement reaction Combination reaction as well as oxidation reaction

Option (d) is the answer. In the above reaction, Metal combines with the oxygen to form a single compound which is a combination reaction and here addition of oxygen takes place so it is oxidation reaction

ChemistryClass 10ICSE

A white precipitate will be obtained if we add common salt solution to: (a) Ba(NO3)2solution (b) KNO3 solution (c)AgNO3solution (d) Mg(NO3)2 solution

Option (c) is the answer. A white precipitate is formed when we add common salt to silver nitrate which is a precipitation reaction.

ChemistryClass 10ICSE

A white precipitate can be obtained by adding sulphuric acid to: (a) CuSO4 solution (b) NaCl solution (c) BaCl2 solution Na2SO4 solution

Option (c) is the answer. When dilute sulphuric acid reacts with the barium chloride then the barium sulphate is formed as a product with hydrochloric gas and thus formed barium sulphate will be white precipitate which is insoluble.

ChemistryClass 10ICSE

In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of: (a) Cl2 (b)H2 (c)N2 (d) O2

Option (c) is the answer. If food items are packed in plastic bags in an atmosphere of nitrogen gas it does not spoil as nitrogen is an inert gas and does not react with the things. This is done to prevent the oxidation of fatty acids and oils present in the chips

ChemistryClass 10ICSE

The term used to indicate the development of unpleasant smell and taste in fat and oil containing food due to aerial oxidation is: (a) Acidity (b)Radioactivity (c)Rabidity (d)Rancidity

Option (d) is the answer. Rancidity is the term used to indicate the development of unpleasant smell and taste in fat and oil containing food due to aerial oxidation and it can be prevented by closely and tight packing of food items in a container which does not allows air to react.

ChemistryClass 10ICSE

The chemical reaction involved in the corrosion of iron metal is that of: (a) Oxidation as well as displacement (b) Reduction as well as combination (c) Oxidation as well as combination Reduction as well as displacement

Option (c) is the answer. Corrosion takes place when iron metal reacts with water and oxygen and form hydrated oxide and is an oxidation reaction as it is adding up of oxygen Iron metal combines with water and oxygen to corrode thus it is a combination reaction which further forms a single compound.

ChemistryClass 10ICSE

In the context of redox reactions, the removal of hydrogen from a substance is known as : (a) Oxidation (b) Dehydration (c) Reduction Dehydrogenation

Option (a) is the answer. In redox reaction both reduction and oxidation takes place and reduction is when hydrogen is added and oxidation is where hydrogen is removed

ChemistryClass 10ICSE

The removal of oxygen from a substance is called (a) Oxidation (b) Corrosion (c) Reduction Rancidity

Option (c) is correct. Reduction is the process of removal of oxygen from a substance and adding of hydrogen. It occurs when the oxidation of atoms decreases

ChemistryClass 10ICSE

What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride? (b) Write the balanced chemical equation for the reaction which takes place. (c) State the physical conditions of reactants in which the reaction will not take place. (d) Name the type of chemical reaction which occurs. Give one example of another reaction which is of the same type as the above reaction.

When barium chloride solution is added to sodium sulphate solution, then a white precipitate of barium sulphate is formed alongwith sodium chloride solution. Na2SO4 + BaCl2 → BaSO4 + 2NaCl Solid sodium sulphate and Solid barium chloride Double displacement Silver nitrate solution and sodium chloride solution forms a white precipitate of silver chloride and sodium nitrate solution.

ChemistryClass 10ICSE

(a) Explain the term "rancidity". What damage is caused by rancidity? (b) What type of chemical reaction is responsible for causing rancidity? State and explain the various methods for preventing or retarding rancidity of food.

Rancidity is the process of slow oxidation of oil and fat present in the food materials resulting in the production of foul odor and taste in When fats and oils are oxidized, the food becomes rancid i.e., their smell and taste changes. Oxidation is the chemical reaction involved in this as it get exposed to air (i) Refrigerate cooked food at low temperatures Pack food items in air tight containers Prevention by adding anti-oxidants like BHA(Buty

ChemistryClass 10ICSE

Explain the term "corrosion" with an example. Write a chemical equation to show the process of corrosion of iron. (b) What special name is given to the corrosion of iron? (c) What type of chemical reaction is involved in the corrosion of iron? (d) Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel.

Corrosion is a natural process that gradually destructs the materials by chemically or by electrochemical reaction within the environment. Corrosion occurs when most or all of the atoms on the same metal surface are oxidized and damaging the entire surface. Rusting of iron is the most common form of corrosion 4Fe + 3O2 + 2H2O → 2Fe2O3.xH2O Rusting Oxidation Statues, cars, buildings

ChemistryClass 10ICSE

What happens when a zinc strip is dipped into a copper sulphate solution? ( Write the equation for the reaction that takes place. Name the type of reaction involved.

Zinc sulphate Solution and copper are obtained when a strip of zinc metal is placed in copper Sulphate Solution. CuSO4(aq.) +Zn(s)→ ZnSO4(aq.) +Cu(s) Displacement reaction takes place where zinc metal displaces as zinc sulphate and copper sulphate to

ChemistryClass 10ICSE

What happens when silver chloride is exposed to sunlight? Write a chemical equation for this reaction. Also give one use of such a reaction.

When silver chloride is exposed to light, it decomposes to form silver metal and chlorine gas which is a photolytic decomposition reaction,decomposition carried out by sunlight. 2AgCl(s) → 2Ag(s) + Cl2 This reaction is used in black and white photography.

ChemistryClass 10ICSE

What happens when silver nitrate solution is added to sodium chloride solution? (a) Write the equation for the reaction which takes place. Name the type of reaction involved.

When silver nitrate solution is added to sodium chloride solution, a white precipitate of silver chloride is formed alongwith sodium nitrate solution. AgNO3 (aq) + NaCl (aq) → AgCl (s)+ NaNO3 (aq) Double displacement reaction that is a chemical reaction where two compounds react and the positive ions and negative ions of the two reactants switch places forming new compounds.

ChemistryClass 10ICSE

In the reaction represented by the following equation: (a) Name the substance oxidised (b) Name the substance reduced (c) Name the oxidising agent Name the reducing agent

H2 (Addition of oxygen dihydrogen) CuO (Removal of oxygen) CuO (Beingreduced) H2(Being oxidized)

ChemistryClass 10ICSE

What happens when a piece of iron metal is placed in copper sulphate solution? Name the type of reaction involved. (b) Write balanced chemical equation with state symbols for the following reaction: Barium chloride solution reacts with sodium sulphate solution to give insoluble barium sulphate and a solution of sodium chloride.

(a) When a piece of iron metal is placed in copper sulphate solution, then magnesium sulphate solution and copper metal are formed. This is a type of displacement reaction. CuSO4 + Fe → FeSO4 + Cu (b) Na2SO4 + BaCl2 → BaSO4 + 2NaCl

ChemistryClass 10ICSE

Why are decomposition reactions called the opposite of combination reactions? Explain with equations of these reactions. (b) Express the following facts in the form of a balanced chemical equation: "When a strip of copper metal is placed in a solution of silver nitrate, metallic silver is precipitated and a solution containing copper nitrate is formed."

The reactions those split or break the compounds into two simpler products are called decomposition reaction Example: decomposition of calcium carbonate into calcium oxide and carbon dioxide when heated CaCO3→ CaO + CO2 They are called opposite of combination reaction because in combination reaction two or more reactants combined to form one single product Example Magnesium and oxygen combine to form magnesium dioxide 2Mg + O2→ 2MgO (b) Cu (s) + 2AgNO

ChemistryClass 10ICSE

What is meant by (a) displacement reaction, and (b) double displacement reaction? Explain with the help of one example each.

Displacement reaction is a reaction in which one active element displaces a less reactive element from its salt solution 2KI + Cl2 → 2KCl + I2 Double displacement reaction is a chemical change in which two ionic compounds are exchanged and make components Fe2O3 + 6HCl → 2FeCl3 + 3H2O

ChemistryClass 10ICSE

Define the following in terms of gain or loss of hydrogen with one example each: (i) Oxidation (ii) reduction (b) When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.

Oxidation is removal of hydrogen and reduction is gaining of hydrogen. By taking an example Fe2O3 + 3CO → 2Fe + 3CO2 Fe got reduced here and Carbon got oxidized by gaining oxygen (b) 2Mg + O2→ 2MgO (i) Substance oxidized is Mg (ii) Substance reduced is O2

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