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ChemistryClass 10ICSE

In the following reaction between lead sulphide and hydrogen peroxide: PbS(s) + 4H2O2(aq) → PbSO4(s) +4H2O(l) (a) Which substance is reduced? Which substance is oxidized?

H2O2 PbS

ChemistryClass 10ICSE

Which of the following is a combination and which a displacement reaction. (a) Cl2 +2KI → 2KCl +I2 (b) 2K + Cl2 → 2KCl

Displacement Combination

ChemistryClass 10ICSE

Balance the following chemical equations: (a) FeSO4→ Fe2O3 + SO2 + SO3 (b) Pb(NO3)2(s) →PbO(s) + NO2(g) + O2

2FeSO4→ Fe2O3 + SO2 + SO3 2Pb(NO3)2(s) → 2PbO(s) + 4 NO2(g) + O2 Both in the presence of heat and decomposition reaction takes place

ChemistryClass 10ICSE

What type of chemical reactions is represented by the following equations? (i) A + BC → AC+ B (ii) A +B → C (iii) X → Y+ Z (iv) PQ + RS → PS + RQ (v) A2O3 + 2B → B2O3 + 2A

Displacement Combination Decomposition Double displacement Displacement

ChemistryClass 10ICSE

What type of chemical reaction stake place when: (a) A magnesium wire is burnt in air? (b) Lime-stone is heated? (c) Silver bromide is exposed to sunlight? (d) Electricity is passed through water? Ammonia and hydrogen chloride are mixed?

(a) Combination. (b) Decomposition. (c) Decomposition. (d) Decomposition. Combination.

ChemistryClass 10ICSE

What type of reactions are represented by the following equations? (i) CaCO3→ CaO + CO2 (ii) CaO + H2O → Ca(OH)2 (iii) 2FeSO4→ Fe2O3 + SO2+ SO3 (iv) NH4Cl → NH3 + HCl (v) 2Ca + O2→ 2CaO

(i) Decomposition. (ii) Combination. (iii) Decomposition. (iv) Decomposition. (v) Combination.

ChemistryClass 10ICSE

Write one equation each for the decomposition reactions where energy is supplied in the form of (a) heat, (b) light, and (c) electricity.

Decomposition reaction when heat is supplied 2Pb(NO3)2→ 2PbO + 4NO2 + O2 Decomposition reaction when light is supplied 2AgCl → 2Ag + Cl2 Decomposition reaction where electricity is supplied 2H2O→ 2H2 + O2

ChemistryClass 10ICSE

What type of chemical reaction is used to extract metals from their naturally compounds like oxides or chlorides?

Decomposition reaction is used to extract several metals from their naturally occurring compounds like oxide and chloride Example: 2NaCl → 2Na + Cl2

ChemistryClass 10ICSE

Name two anti-oxidants which are usually added to fat and oil containing foods to prevent rancidity.

Anti-oxidants are used as preservatives in fat containing foods to slow up the development of rancidity due to oxidation Butylated hydroxytoluene (BHT) and Butylated hydroxyanisole (BHA) can also be used as anti-oxidants with greater half-life than natural anti-oxidants.

ChemistryClass 10ICSE

Give one example of a decomposition reaction which is carried out: (a) With electricity By applying heat

When electricity is passed through acidified water it decomposes to Hydrogen and oxygen gas 2H2 O → 2H2 + O2 By applying heat, thermal decomposition takes place 2NaHCO3(s) → CO2(g) + H2O(g) + Na2CO3(s) Heating of baking soda is an example

ChemistryClass 10ICSE

Explain why, food products containing fats and oils (like potato chips) are packaged in nitrogen.

The packet of chips or foods containing fats and oils are flushed with nitrogen. This is because nitrogen acts as a antioxidant and this packaging is to prevent the food products from being oxidized. If we pack with oxygen it reacts and become rancid and the smell and taste will change and will start to decay.

ChemistryClass 10ICSE

What are anti-oxidants? Why are they added to fat and oil containing foods?

Anti-oxidants are the chemicals which are added to fat and oil containing foods to slow or delay the development of rancidity. Natural Anti-oxidants are ascorbic acid ad tocopherols whereas synthetic anti- oxidants include Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Anti-oxidants can be nutrients as well as enzymes that are especially proteins that can assist in chemical reaction and prevent development such as cancer,heart attack and many other chronic diseases

ChemistryClass 10ICSE

State an important use of decomposition reactions.

Decomposition of silver chloride into silver and chlorineby light is used in photography. In the human body, this reaction helps in digestion of food in the stomach. Decomposition reaction is used in the manufacture of cement and gypsum. This reaction is used in the process of welding.

ChemistryClass 10ICSE

What is the general name of the chemicals which are added to fat and oil containing foods to prevent the development of rancidity?

Anti-oxidants are the chemicals which are added to fat and oil containing foods to slow or delay the development of rancidity. Natural Anti-oxidants are ascorbic acid ad tocopherols whereas synthetic anti- oxidants include Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT)

ChemistryClass 10ICSE

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

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