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Which term is used to indicate the development of unpleasant smell and taste in fat and oil containing foods due to aerial oxidation (when they are kept exposed for a considerable time)?

Rancidity is the term used and this condition is produced by aerial oxidation of unsaturated fat present in food and other products. It is incomplete oxidation of fats and oils when exposed to air, light or moisture

ChemistryClass 10ICSE

Write the balanced chemical equation for the following reaction: Zinc + Silver nitrate Zinc nitrate + Silver

Zn + 2AgNO3 → Zn(NO3)2 + 2Ag

ChemistryClass 10ICSE

Why does the colour of copper sulphate solution change when an iron nail is kept immersed in it?

It is a displacement reaction. Copper sulphate solution changes its colour because iron nail dipped in the solution is more reactive than copper sulphate and it displaces the molecules. The copper gets deposited over the nail as the copper sulphate solution becomes iron sulfate solution and colour changes from blue to green

ChemistryClass 10ICSE

Name the various types of chemical reactions.

There are many types of chemical reactions. Here are the names: Combination Decomposition Displacement Double displacement Oxidation and reduction

ChemistryClass 10ICSE

What type of reaction is represented by the digestion of food in our body?

Decomposition reaction is the reaction which is represented by the digestion of our body it is nothing but a chemical reaction where food what we are having is further break down into digestible nutrients such as fats, proteins and carbohydrates which is essential for the proper functioning of a human body

ChemistryClass 10ICSE

Gas A, which is the major cause of global warming, combines with hydrogen oxide B in nature in the presence of an environmental factor C and a green material D to form a six carbon organic compound E and a gas F. The gas F is necessary for breathing. (a) What is gas A? (b) What is the common name B? (c) What do you think could be C? (d) What is material D? Where is it found? (e) Name the organic compound E. What is gas F? Name the natural process during which it is released.

Gas A is Carbon dioxide, CO2 B is Water, H2O Sunlight is the environmental factor Material D is Chlorophyll; it is found in green leaves of plants which provide pigmentation Organic compound E is Glucose, C6H12O6 F is Oxygen; Photosynthesis is the process where Oxygen is released

ChemistryClass 10ICSE

The white solid compound A decomposes quite rapidly on heating in the presence of a black substance X to form a solid compound B and a gas C. When an aqueous solution of compound B is reacted with silver nitrate solution, then a white precipitate of silver chloride is obtained alongwith potassium nitrate solution. Gas C does not burn itself but helps burn things. (a) What is compound A? (b) What is compound B? (c) What is gas C? (d) What do you think is the black substance X? What is its function? What is the general name of substance like X?

Compound A is Potassium chlorate, KClO3 Compound B is Potassium chloride, KCl Gas C is Oxygen, O2 X is Manganese dioxide, MnO2; Manganese dioxide is used as a catalyst in order to enhance the reaction Catalysts are the general name for substances like X

ChemistryClass 10ICSE

When a mixture of gases X and Y is compressed to 300 atm pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300oC), then an organic compound Z having the molecular formula CH4O is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas. (a) What are X, Y and Z? (b) Write a balance chemical equation of the reaction which takes place When X and Y combine to form Z. Indicate the conditions under which the reaction occurs.

(a) X= Carbon monoxide gas (CO); Y= Hydrogen gas (H2); Z = Methanol (CH3OH or CH4O) (b)CO(g) + 2H2(g) → CH3OH (l) Carbon monoxide when reacts with hydrogen gas under a pressure of 300atmosphere and a temperature of 300℃ and a catalyst which is a mixture of Zinc oxide and chromium oxide

ChemistryClass 10ICSE

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors. (a) What is metal M? (b) What is solution S? Is it acidic or alkaline? (c) What is gas G? (d) Write a balanced chemical equation for the reaction which takes place when metal M reacts with water. Is this reaction exothermic or endothermic?

Sodium is the metal ( Na ) Solution S is Sodium hydroxide solution (NaOH solution),It is Hydrogen, H2is the gas evolved 2Na + 2H2O → 2NaOH + H2 Reaction is

ChemistryClass 10ICSE

A metal X forms a salt XSO4. The salt XSO4 forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wires and alloys like brass. (a) What do you think metal X could be? (b) Write the name, formula and colour of salt XSO4. (c) What is the blue precipitate Y? (d) Write a chemical equation of the reaction which takes place When salt XSO4 reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

Metal could be Copper, Copper sulphate, CuSO4, Blue The blue precipitate Y is Copper hydroxide, Cu(OH)2 CuSO4 (aq) + 2NaOH (aq) → Cu(OH)2 (s) + Na2S04 (aq)

ChemistryClass 10ICSE

A silvery-white metal X taken in the form of ribbon, when ignited, burns in air with a dazzling white flame to form a white powder Y. When water is added to powder Y, it dissolves partially to form another substance Z. (a) What could metal X be? (b) What is powder Y? (c) With which substance metal X combines to form powder Y? (d) What is substance Z? Name one domestic use of substance Z. (e) Write a balanced chemical equation of the reaction which takes place When metal X burns in air to form powder Y.

Magnesium, Magnesium oxide, MgO Oxygen (of air), O2 Magnesium hydroxide, Mg(OH)2; Used as antacid to relieve indigestion 2Mg + O2→ 2MgO

ChemistryClass 10ICSE

A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P. (a) What is substance P? Write its common name as well as chemical formula. (b) What is substance Q? (c) What is gas R? (d) What is substance S? what is its clear solution known as? What is substance T? Name any two natural forms in which substance T occurs in nature.

Calcium carbonate (limestone), CaCO3 Calcium oxide, CaO Carbon dioxide, CO2 Calcium hydroxide, Ca(OH)2; Lime Calcium carbonate; Limestone and Marble.

ChemistryClass 10ICSE

When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion. (a) Name any two metals which can behave like metal X. (b) Name any two acids which can behave like acid Y. (c) Name the gas Z. (d) Is the gas Z lighter than or heavier than air? (e) Is the reaction between metal X and dilute acid Y exothermic or endothermic? (f) By taking a specific example of metal X and dilute acid Y, Write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.

Zinc and Dilute hydrochloric acid and dilute sulphuric Lighter than Suppose metal X is zinc (Zn) and acid Y is dilute hydrochloric acid (HCl) ; Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)

ChemistryClass 10ICSE

When water is added gradually to a white solid X, a hissing sound and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory. (a) What could be solid X? Write its chemical formula. (b) What could be product Y? Write its chemical formula. (c) What is the common name of the solution of Y which is used for testing carbon dioxide gas? (d) Write chemical equation of the reaction which takes place on adding water to solid X. (e) Which characteristics of chemical reactions are illustrated by this example?

Calcium oxide, Calcium hydroxide, Ca(OH)2 Lime CaO + H2O → Ca(OH)2 Change in

ChemistryClass 10ICSE

When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution. (a) What do you think substance X is likely to be? (b) Name the substance which the yellow solid consists of. (c) Which characteristic of chemical reactions is illustrated by this example? (d) Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactants and products involved in the chemical equation.

Lead Nitrate Lead Iodide Formation of precipitate Pb(NO3)2 (aq) + 2KI (aq) → PbI2 (s) + 2KNO3 (aq)

ChemistryClass 10ICSE

The chemical equations are balanced to satisfy one of the following laws in chemical reactions. This law is known as: (a) Law of conservation of momentum (b) Law of conservation of mass (c) Law of conservation of motion Law of conservation of magnetism

Option (b) is the answer. Equations are balanced when the mass of atoms of different element in reactants side equal to the products side.

ChemistryClass 10ICSE

One of the following is an exothermic reaction. This is: (a) Electrolysis of water (b) Conversion of limestone into quicklime (c) Process of respiration (d) Process of photosynthesis

Option (c) is the answer. Respiration is an exothermic reaction as the heat energy is released which maintains our body temperature.

ChemistryClass 10ICSE

Which of the following is not an endothermic reaction ? (a) CaCO3→ CaO + CO2 (b) 2H2O → 2H2 + O2 (c) 6CO2 + 6H2O → C6H12O6 + 6O2 (d) C6H12O6 + 6O2→ 6CO2 + 6H2O

Option (d) is the answer. This is responsible for the respiration reaction in which glucose burns in oxygen to produce heat energy and thus an exothermic reaction

ChemistryClass 10ICSE

One of the following is an endothermic reaction. This is: (a) Combination of carbon and oxygen to form carbon monoxide (b) Combination of nitrogen and oxygen to form nitrogen monoxide (c) Combination of glucose and oxygen to form carbon dioxide and water Combination of zinc and hydrochloric acid to form zinc chloride and hydrogen

Option (b) is the answer. When nitrogen and oxygen are heated at very high temperature they form nitrogen monoxide and it is a endothermic reaction.

ChemistryClass 10ICSE

The chemical reaction between quicklime and water is characterised by: (a) Evolution of hydrogen gas (b) Formation of slaked lime precipitate (c) Change in temperature of mixture Change in colour of the product

Option (c) is the answer. Reaction of quicklime and water releases higher amount of energy and thus it is an exothermic reaction.

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