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ChemistryClass 10ICSE

Which of the following salt will give an aqueous solution having pH of almost 7? (a) NH4NO3 (b) NH4Cl (c) CaCl2 KCl

Option (d) is the answer.

ChemistryClass 10ICSE

A salt is dissolved in water and the pH of this salt solution is measured with a universal indicator paper. If the pH of the solution is less than 7, the salt is most likely to be: (a) CH3COONa (b) Na2CO3 (c) KCl (d) NH4Cl

Option (d) is the answer.

ChemistryClass 10ICSE

A salt whose aqueous solution will have a pH of more than 7 will be: (a) K2CO3 (b) K2SO4 (c) NaCl (d) NH4Cl

Option (a) is the answer.

ChemistryClass 10ICSE

Plaster of paris is prepared by heating one of the following to a temperature of 100℃. This is: (a) CaSO3.2H2O (b) CaCl2.2H2O (c) CaCO3.2H2O (d) CaSO4.2H2O

Option (d) is the answer.

ChemistryClass 10ICSE

Which of the following is treated with chlorine to obtain bleaching powder? (a) CaSO4 (b) Ca(OH)2 (c) Mg(OH)2 (d) KOH

Option (b) is the answer.

ChemistryClass 10ICSE

The formula of baking soda is: (a) K2CO3 (b) KHCO3 (c) NaHCO3 (d) KNO3

Option (c) is the answer.

ChemistryClass 10ICSE

The aqueous solution of one of the following salt will turn phenolphthalein indicator pink. This salt is: (a) KCl (b) K2SO4 (c) K2CO3 (d) KNO3

Option (c) is the answer.

ChemistryClass 10ICSE

The salt whose aqueous solution will have no effect on either red litmus or blue litmus is (a) Potassium sulphate (b) Sodium carbonate (c) Ammonium sulphate Sodium acetate

Option (a) is the answer.

ChemistryClass 10ICSE

The aqueous solution of one of the following salt will turn red litmus to blue. This salt is: (a) Potassium sulphate (b) Sodium sulphate (c) Sodium chloride Potassium carbonate

Option (d) is the answer.

ChemistryClass 10ICSE

The salt whose aqueous solution will turn blue litmus to red is: (a) Ammonium sulphate (b) Sodium acetate (c) Sodium chloride Potassium carbonate

Option (a) is the answer.

ChemistryClass 10ICSE

The number of molecules of water of crystallisation present in washing soda crystals is: (a) Five (b) Two (c) Ten Seven

Option (c) is the answer.

ChemistryClass 10ICSE

The products of chlor-alkali process are: (a) NaCl, Cl2 , and H2 (b) Cl2 , H2 and NaOH (c) Cl2, Na2CO3 and H2O NaOH, Cl2 and HCl

Option (b) is the answer.

ChemistryClass 10ICSE

The salt which give a neutral solution on dissolving in water will be: (a) CH3COONa (b) NH4Cl (c) KCl (d) Na2CO3

Option (c) is the answer.

ChemistryClass 10ICSE

One of the following salt will give an alkaline solution on dissolving in water. This is: (a) Na2CO3 (b) Na2SO4 (c) NaCl (d)(NH4)2SO4

Option (a) is the answer.

ChemistryClass 10ICSE

The salt which will give an acidic solution on dissolving in water is: (a) KCl (b) NH4Cl (c) Na2CO3 (d) CH3COONa

Option (b) is the answer.

ChemistryClass 10ICSE

What is a salt? Give the names and formulae of any two salts. Also name the acids and bases from which these salts may be obtained. (b) What is meant by 'a family of salts'? Explain with examples. (c) What is meant by 'hydrated' and 'anhydrous' salts? Explain with examples. (d) Write the names, formulae and colours of any two hydrated salts. What will be the colour of litmus in an aqueous solution of ammonium chloride salt?

A salt is a compound when a metal replaces the hydrogen atom in an Example: Sodium chloride NaCl; It is obtained from hydrochloric acid and sodium metal. Ammonium chloride NH4Cl; It is obtained from ammonia and hydrochloric acid. The salt having same positive ions are said to belong to a family of Sodium chloride and sodium sulphate are the examples of family of salts The salts which contains water of crystallization are called hydrated salt Example: Copper sulphate crystals contain 5 molecules of water of crystallization Copper sulphate pentahydrate salt - Its chemical formula is CuSO4.5H2 It is blue in colour. Iron sulphate heptahydrate salt - Its chemical formula is FeSO4.7H2O. It is green in colour. Colour of litmus turns red in an aqueous solution of ammonium chloride

ChemistryClass 10ICSE

What is plaster of Paris? Write the chemical formula for plaster of Paris. (b) How is plaster of Paris prepared? Write chemical equation of the reaction involved. (c) Explain why plaster of Paris should be stored in a moisture-proof container. Write two important uses of plaster of Paris.

Plaster of Paris is called calcium sulphate hemihydrate which is a hard substance made by the addition of water and gypsum. CaSO1/2H2O is the formula It is prepared by heating gypsum to a temperature at 373K and it loses 3/4th of its water of crystallisation and forms Plaster of Paris CaSO4.2H2O → CaSO4.1/2H2O + 1 1/2H2O The presence of moisture can cause the slow setting of plaster of Paris by bringing about its hydration Used for healing the fracture of bones Used as fire proofing material.

ChemistryClass 10ICSE

What is bleaching powder? How is bleaching powder prepared? Write chemical equation of the reactions involved. (b) What happens when bleaching powder reacts with dilute sulphuric acid? Give equation of the reaction involved. Write two important uses of bleaching powder.

Bleaching powder is calcium oxychloride(CaOCl2). It is prepared by passing chlorine gas over a dry slaked lime Ca(OH)2 + Cl2 → CaOCl2 + H2O When bleaching powder reacts with sulphuric acid, it liberates chlorine CaOCl2 + H2SO4 → CaSO4 + Cl2 + H2O (i) Used as disinfectant Used in the manufacturing of chloroform

ChemistryClass 10ICSE

Describe how washing soda is produced starting from sodium chloride (common salt). Write equations of all the reactions involved. (b) State whether an aqueous solution of washing soda is acidic or alkaline. Give reason for your answer. (c) What is meant by saying that washing soda has detergent properties? Mention two important uses of washing soda (or sodium carbonate).

Washing soda is produced from sodium chloride Step 1: A cold and concentrated solution of sodium chloride called brine is reacted with ammonia and carbon dioxide to obtain sodium hydrogencarbonate NaCl + NH3 + H2O + CO2 → NaHHCO3 + NH4Cl Step 2: Sodium hydrogencarbonate formed is separated by filtration dried and heated. It further decomposes to sodium carbonate 2NaHCO3 → Na2CO3 + CO2 + H2O Anhydrous sodium carbonate is called soda ash Step 3: Soda ash is then dissolved in water and recrystallized to get washing soda crystals containing 10 molecules of water of crystallization Na2CO3 + 10H2O → Na2CO3.10H2O An aqueous solution of washing soda is alkaline because it turns red litmus to blue Washing soda has a cleansing and detergent property thus it removes dirt and grease from dirty clothes Used as cleansing agent Used to remove permanent hardness of water

ChemistryClass 10ICSE

What happens when a concentrated solution of sodium chloride (brine) is electrolysed? Write the equation of the reaction involved. (b) Why is the electrolysis of a concentrated solution of sodium chloride known as chlor-alkali process? Name three products of the chlor-alkali process. State two uses of each of these products.

when a concentrated solution of sodium chloride is electrolysed, it decomposes to form sodium hydroxide, chlorine and hydrogen → 2NaCl(aq) + Cl2(g) + H2(g) 2NaCl(aq) + 2HCl(l) The electrolysis of a concentrated solution of sodium chloride is known as chlor-alkali because of the products formed, Chlorine and hydrogen. Sodium hydroxide, chlorine and hydrogen Sodium hydroxide: Used for making soaps Manufacturing of paper Chlorine Used in the production of bleaching powder Used for sterilising drinking water Hydrogen Used as fuels in rockets Used in hydrogenation of oils

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