1. What is common to all acids? (1 mark)
2. A white chemical compound becomes hard on mixing proper quantity of water. It is also used in surgery to maintain joins in a fixed position. Name the chemical compound. (1 mark)
3. Name two constituents of baking power. (1 mark)
4. A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical material which he can mix the soil to adjust its pH. (1 mark)
5. Write the pH value, after which teeth start decaying? (1 mark)
6. How is the concentration of hydroxide ions (OH-) affected when excess base is dissolved in a solution of sodium hydroxide? (2 marks)
7. A white substance having a strong smell of chlorine is used to clean water in water storage tank.
Identify the substance. Write its chemical name and the reaction for its preparation. (2 marks)
8. How is plaster of Paris obtained? What reaction is involved in the setting of a paste of plaster of
Paris. (2 marks)
9. Name the gas evolved when dilute sulphuric acid acts on sodium carbonate. Writ the chemical equation for the reaction involved. (2 marks).
10. What is meant by the term ‘pH of a solution’? The pH of gastric juices extracted from he stomach of two persons A and B were found to be 1 and 3 respectively. The stomach juice of which person is more acidic? (2 marks)
11. Fresh milk has pH of 6. How do you think the pH will change as it becomes sour? Explain your answer. (2 marks)
12. (i) Write the chemical names and formula of bleaching powder.
(ii) Why does bleaching powder smell of chlorine when exposed to air?
(iii) Write chemical equation to represent the action of dilute hydrochloric acid on bleaching powder. (3 marks)
13. What happens when
(i) Aluminium metal reacts with dilute HCI? (ii) Potassium oxide is dissolved in water?
(iii) Sodium hydroxide reacts with sulphuric acid completely?
Give equation for the chemical reactions involved. (3 marks)
14. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example.
How will you test for the presence of he gas? (3 marks)
________________________________________________________________
1. What is the name given to a reaction between an acid and a base? (1 mark)
2. Name the raw materials used for preparing bleaching powder. (1 mark)
3. What is the chemical name and chemical formula of baking soda? (1 mark)
4. Under what soil conditions do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)? (1 mark)
5. What effect does the concentration of H+ (aq) have on the acidic nature of the solution? (1 mark)
6. A house-wife found that the cake prepared by her in hard and small in size. Which ingredient has she forgotten to add that would have made the cake fluffy. Give reason. (2 marks)
7. Equal lengths of magnesium ribbon are taken in test tubes ‘A’ and ‘B’. Hydrochloric acid (HCI) is added to test-tube A while acetic acid (CH3COOH) is added to test-tube ‘B’. In which test- tube will the fizzing occur more vigorously and why? (2 marks)
8. Plaster of Paris should be stored in a moisture – proof container. Explain why? (2 marks)
9. Why do HCI, HNO3, etc. show acidic characters in aqueous solutions while solution of compounds like alcohol and glucose do not show acidic character? (2 marks)
10. You have been provided that three test-tubes? One of them contains distilled water and the other two contains an acidic solution and a basic solution respectively. If you are given red litmus paper, how will you identify contents of each test-tube? (3 marks)
11. A milkman adds a very small amount of baking soda to fresh milk” (3 marks) (i) Why does he shift the pH of the fresh from ‘6’ to slightly alkaline?
(ii) What do you expect to observe when this milk comes to boil? (iii) Why does this milk take a long time to set as cur?
12. A compound X of sodium form a white powder. It is a constituent of baking powder and is used in some antacid prescriptions. When heated, X gives out of a gas and steam. The gas forms a white precipitate with lime water. Write the chemical formula and name of X and the chemical equation for its decomposition on heating. What is its role in baking powder and in antacids.
(3 marks)
13. (a) What is acid rain? How does it affect our aquatic life? (b)What happens during a bee sting? What is its remedy?
(c)Two solutions X and Y are tested with universal indicator. Solution X turns orange whereas solution Y turns red. Which of the solution is a stronger acid? (5 marks)
_____________________________________________________________
1. Why does an aqueous solution of an acid conduct electricity? (1 marks)
2. Why does dry HCI gas not change the colour of the dry litmus paper? (1 marks)
3. What is the common name of the compound CaOCI2? (1 marks)
4. Write an equation to show the reaction between plaster of Paris and water. (1 marks)
Which element is common to all acids?
5. Which gas is usually liberated when an acid reacts with a metal? (1 marks)
6. In textile mills, a white substance having a strong smell of chlorine in used o remove yellowness of white cloths. Identify the substance. How is it prepared? Write chemical equation of he reaction involved. (2 marks)
7. What happens when crystals of washing soda are left open in dry air? What is this change named as? Name two industries based on use of washing soda. (2 marks)
8. Give Arrhenius definition of an acid and a base. Choose strong acid and strong base from the following: (2 marks)
CH3COOH, NH4OH, KOH, HCI.
9. Sate the chemical property in each case on which the following uses of baking soda are based.
(i) as an antacid.
(ii) as a constituent of baking powder. (2 marks)
10. Why does distilled water not conduct electricity, whereas rain water does? (3 marks)
11. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCI) is added to test tube A, while acetic acid (CH3 COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why? (3 marks)
12. Identify the compounds of calcium which is yellowish white powder and is used for disinfecting drinking water. How is it manufactured? White the chemical equation for the reaction involved. What happens when it is left exposed to air? (3 marks)
13. (i) Distinguish between acid and alkali. (ii)Distinguish between base and alkali.
(iii)1 mole per litre of (A) has pH equal to 13 and 1 mole per litre of (B) has pH equal to 11. Which is stronger? Are these bases or acids? (5 marks)
_______________________________________
1. Three solutions A, B and C have pH, values of 6, 4 and 10 respectively. Which of the solution is highly acidic? (1 mark)
2. Two solutions X and Y have pH = 4 and pH = 8 respectively. Which solution will give alkaline reaction and which one acidic. (1 mark)
3. A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical materials which he can mix with soil with soil to adjust its pH. (1 mark)
4. State the chemical name and formula of common salt. (1 mark)
5. ‘Sweet tooth’ may lead to tooth decay. Explain why? What is the role of tooth paste in preventing cavities? (2 marks)
6. Write the reaction that takes place when sodium oxide reacts with water. How will this solution behave towards phenolphthalein and red litmus paper? (2 marks)
7. Why should curd and sour substances not be kept in brass and copper vessels? (2 marks)
8. How is the concentration of hydronium ions (H2O+) affected when a solution of an acid is diluted? (2 marks)
9. Why do acids not show acidic behavior in the absence of water? (2 marks)
10. Identify the compound of calcium which is used for plastering of fractured bones. With the help of chemical equation, describe how this compound is prepared. What special precaution should be taken during the preparation of this compound? (3 marks)
12.
(i)
Why should curd and sour substances no be kept in brass and copper vessels.
(ii)
The pH of hydrochloric acid solution is 3. Does it mean that it has only hydronium ions. If not, how are OH- ions generated?
(iii)
Distinguish between acid and alkali. (5 marks)
11. State Arrhenius Concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances: (3 marks) H2CO3, HNO3, NaOH, NH4OH
Compounds like alcohol and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.
_______________________________________________________________
1. What is the chemical name of washing soda? (1mark)
2. When sodium hydrogen carbonate is added to water, the hydrogen ion concentration decreases.
What is the nature of the solution? Acidic or basic? (1mark)
3. Write the chemical name and formula of bleaching powder. (1mark)
4. A milkman adds a very small amount of baking soda to fresh milk. (2 marks) (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
5. Plaster of Paris should be stored in a moisture proof container. Explain why? (2 marks)
6. What is a neutralization reaction? Give two examples. (2 marks)
7. Explain how pH change in the river water can endanger the lives of aquatic animals like fish.
8. What happens when (2 marks) (i) plaster of Paris is heated to 473 K? (ii) plaster of Paris is mixed with water?
9. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example.
How will you test for the presence of this gas? (3 marks)
10. Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented? (3 marks)
11. Name the raw material used for the preparation of plaster of Paris. Write an equation to show the reaction between Plaster of Paris and water. What will happen if heating is not controlled while preparing plaster of Paris? (3 marks)
12. (i) Why are acids not stored in meal containers? Containers made from which material are safe to store acids.
(ii) Explain why does dry hydrochloric acid not conduct electricity but its aqueous solution conducts electricity.
(iii) Why are commercial samples of bleaching powder not completely soluble in water?
Or
Write one activity to show the reaction of acids with metal carbonates/bicarbonates salts.
(5 marks)
2. A white chemical compound becomes hard on mixing proper quantity of water. It is also used in surgery to maintain joins in a fixed position. Name the chemical compound. (1 mark)
3. Name two constituents of baking power. (1 mark)
4. A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical material which he can mix the soil to adjust its pH. (1 mark)
5. Write the pH value, after which teeth start decaying? (1 mark)
6. How is the concentration of hydroxide ions (OH-) affected when excess base is dissolved in a solution of sodium hydroxide? (2 marks)
7. A white substance having a strong smell of chlorine is used to clean water in water storage tank.
Identify the substance. Write its chemical name and the reaction for its preparation. (2 marks)
8. How is plaster of Paris obtained? What reaction is involved in the setting of a paste of plaster of
Paris. (2 marks)
9. Name the gas evolved when dilute sulphuric acid acts on sodium carbonate. Writ the chemical equation for the reaction involved. (2 marks).
10. What is meant by the term ‘pH of a solution’? The pH of gastric juices extracted from he stomach of two persons A and B were found to be 1 and 3 respectively. The stomach juice of which person is more acidic? (2 marks)
11. Fresh milk has pH of 6. How do you think the pH will change as it becomes sour? Explain your answer. (2 marks)
12. (i) Write the chemical names and formula of bleaching powder.
(ii) Why does bleaching powder smell of chlorine when exposed to air?
(iii) Write chemical equation to represent the action of dilute hydrochloric acid on bleaching powder. (3 marks)
13. What happens when
(i) Aluminium metal reacts with dilute HCI? (ii) Potassium oxide is dissolved in water?
(iii) Sodium hydroxide reacts with sulphuric acid completely?
Give equation for the chemical reactions involved. (3 marks)
14. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example.
How will you test for the presence of he gas? (3 marks)
________________________________________________________________
1. What is the name given to a reaction between an acid and a base? (1 mark)
2. Name the raw materials used for preparing bleaching powder. (1 mark)
3. What is the chemical name and chemical formula of baking soda? (1 mark)
4. Under what soil conditions do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)? (1 mark)
5. What effect does the concentration of H+ (aq) have on the acidic nature of the solution? (1 mark)
6. A house-wife found that the cake prepared by her in hard and small in size. Which ingredient has she forgotten to add that would have made the cake fluffy. Give reason. (2 marks)
7. Equal lengths of magnesium ribbon are taken in test tubes ‘A’ and ‘B’. Hydrochloric acid (HCI) is added to test-tube A while acetic acid (CH3COOH) is added to test-tube ‘B’. In which test- tube will the fizzing occur more vigorously and why? (2 marks)
8. Plaster of Paris should be stored in a moisture – proof container. Explain why? (2 marks)
9. Why do HCI, HNO3, etc. show acidic characters in aqueous solutions while solution of compounds like alcohol and glucose do not show acidic character? (2 marks)
10. You have been provided that three test-tubes? One of them contains distilled water and the other two contains an acidic solution and a basic solution respectively. If you are given red litmus paper, how will you identify contents of each test-tube? (3 marks)
11. A milkman adds a very small amount of baking soda to fresh milk” (3 marks) (i) Why does he shift the pH of the fresh from ‘6’ to slightly alkaline?
(ii) What do you expect to observe when this milk comes to boil? (iii) Why does this milk take a long time to set as cur?
12. A compound X of sodium form a white powder. It is a constituent of baking powder and is used in some antacid prescriptions. When heated, X gives out of a gas and steam. The gas forms a white precipitate with lime water. Write the chemical formula and name of X and the chemical equation for its decomposition on heating. What is its role in baking powder and in antacids.
(3 marks)
13. (a) What is acid rain? How does it affect our aquatic life? (b)What happens during a bee sting? What is its remedy?
(c)Two solutions X and Y are tested with universal indicator. Solution X turns orange whereas solution Y turns red. Which of the solution is a stronger acid? (5 marks)
_____________________________________________________________
1. Why does an aqueous solution of an acid conduct electricity? (1 marks)
2. Why does dry HCI gas not change the colour of the dry litmus paper? (1 marks)
3. What is the common name of the compound CaOCI2? (1 marks)
4. Write an equation to show the reaction between plaster of Paris and water. (1 marks)
Which element is common to all acids?
5. Which gas is usually liberated when an acid reacts with a metal? (1 marks)
6. In textile mills, a white substance having a strong smell of chlorine in used o remove yellowness of white cloths. Identify the substance. How is it prepared? Write chemical equation of he reaction involved. (2 marks)
7. What happens when crystals of washing soda are left open in dry air? What is this change named as? Name two industries based on use of washing soda. (2 marks)
8. Give Arrhenius definition of an acid and a base. Choose strong acid and strong base from the following: (2 marks)
CH3COOH, NH4OH, KOH, HCI.
9. Sate the chemical property in each case on which the following uses of baking soda are based.
(i) as an antacid.
(ii) as a constituent of baking powder. (2 marks)
10. Why does distilled water not conduct electricity, whereas rain water does? (3 marks)
11. Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCI) is added to test tube A, while acetic acid (CH3 COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why? (3 marks)
12. Identify the compounds of calcium which is yellowish white powder and is used for disinfecting drinking water. How is it manufactured? White the chemical equation for the reaction involved. What happens when it is left exposed to air? (3 marks)
13. (i) Distinguish between acid and alkali. (ii)Distinguish between base and alkali.
(iii)1 mole per litre of (A) has pH equal to 13 and 1 mole per litre of (B) has pH equal to 11. Which is stronger? Are these bases or acids? (5 marks)
_______________________________________
1. Three solutions A, B and C have pH, values of 6, 4 and 10 respectively. Which of the solution is highly acidic? (1 mark)
2. Two solutions X and Y have pH = 4 and pH = 8 respectively. Which solution will give alkaline reaction and which one acidic. (1 mark)
3. A farmer has found that the pH of soil in his fields is 4.2. Name any two chemical materials which he can mix with soil with soil to adjust its pH. (1 mark)
4. State the chemical name and formula of common salt. (1 mark)
5. ‘Sweet tooth’ may lead to tooth decay. Explain why? What is the role of tooth paste in preventing cavities? (2 marks)
6. Write the reaction that takes place when sodium oxide reacts with water. How will this solution behave towards phenolphthalein and red litmus paper? (2 marks)
7. Why should curd and sour substances not be kept in brass and copper vessels? (2 marks)
8. How is the concentration of hydronium ions (H2O+) affected when a solution of an acid is diluted? (2 marks)
9. Why do acids not show acidic behavior in the absence of water? (2 marks)
10. Identify the compound of calcium which is used for plastering of fractured bones. With the help of chemical equation, describe how this compound is prepared. What special precaution should be taken during the preparation of this compound? (3 marks)
12.
(i)
Why should curd and sour substances no be kept in brass and copper vessels.
(ii)
The pH of hydrochloric acid solution is 3. Does it mean that it has only hydronium ions. If not, how are OH- ions generated?
(iii)
Distinguish between acid and alkali. (5 marks)
11. State Arrhenius Concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances: (3 marks) H2CO3, HNO3, NaOH, NH4OH
Compounds like alcohol and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.
_______________________________________________________________
1. What is the chemical name of washing soda? (1mark)
2. When sodium hydrogen carbonate is added to water, the hydrogen ion concentration decreases.
What is the nature of the solution? Acidic or basic? (1mark)
3. Write the chemical name and formula of bleaching powder. (1mark)
4. A milkman adds a very small amount of baking soda to fresh milk. (2 marks) (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
5. Plaster of Paris should be stored in a moisture proof container. Explain why? (2 marks)
6. What is a neutralization reaction? Give two examples. (2 marks)
7. Explain how pH change in the river water can endanger the lives of aquatic animals like fish.
8. What happens when (2 marks) (i) plaster of Paris is heated to 473 K? (ii) plaster of Paris is mixed with water?
9. Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example.
How will you test for the presence of this gas? (3 marks)
10. Explain the pH change as the cause of tooth decay. How can tooth decay caused by pH change be prevented? (3 marks)
11. Name the raw material used for the preparation of plaster of Paris. Write an equation to show the reaction between Plaster of Paris and water. What will happen if heating is not controlled while preparing plaster of Paris? (3 marks)
12. (i) Why are acids not stored in meal containers? Containers made from which material are safe to store acids.
(ii) Explain why does dry hydrochloric acid not conduct electricity but its aqueous solution conducts electricity.
(iii) Why are commercial samples of bleaching powder not completely soluble in water?
Or
Write one activity to show the reaction of acids with metal carbonates/bicarbonates salts.
(5 marks)
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