Acid, Base and Salt

10 Acid, Base and Salt

1 mark questions

1. What is acid? Give one example.
Ans: Acids are the substances that produce hydrogen ions(H⁺) in aqueous solution .
E.g: HCl
2. What is base? Give one example.
Ans: Base is a oxide and hydroxide of metals that gives hydroxide (OH^-) ion when dissolved in water. Eg: NaOH.
3. What is Salt? Give one example.
Ans: Slat is a compound formed by the partial or complete replacement of on e or more hydrogen atoms of an acid by one or more metal(s) atom or electropositive radical(s). Eg: NaCl
4. What is alkali? Give one example.
Ans: Water soluble base or hydroxide are called alkalis. Eg: NaOH, KOH etc.
5. What is neutralization reaction?
Ans: When an acid reacts with base, it forms a neutral substance i.e salt and water. They are neither acidic nor basic in nature. This type of reaction is called neutralization reaction. 
6. Write down a name and molecular formula of an alkali which is used to reduce acidity of human stomach.
Ans: Milk of magnesia  [Mg(OH)₂] and Aluminum hydroxide[Al(OH)₃] is an alkali which is used to reduce acidity of human stomach.
7. What do you understand by a pH scale?
Ans: A PH scale is the scale that shows the quantity of H⁺ ions in the acid or base. It is used to measure the strength of acidity or alkalinity or neutrality of a substance. This scale consists numbers from 1 to 14 with corresponding colours in the scale. 
8. What is strong acid?
Ans: The acid that ionizes completely and gives large amount of H⁺ ions when dissolved in water is called strong acid. Eg. HCl, H₂So₄ etc. 
9. What is weak acid?
Ans: The acid that does ionizes completely or ionizes partially and gives less amount of H⁺ ions when dissolved in water is called strong acid. Eg. HCOOH, CH₃COOH etc. 
10. Which base is used to neutralize acidic soil?
Ans: Lime (CaO) is a type of base. It is used to neutralize the acidic soil.
11. What is an indicator?
Ans: An indicator is chemical compound that is used ot identify whether the given substance is acid, base or salt. Eg. litmus paper, methyl orange, phenolphthalein etc. 
12. What is the PH value of water?
Ans: The PH value of water is 7. 
13. Which colour for the PH value of water?
Ans: The colour for the PH value of water is green.
14. What is the PH value of normal soil?
And: The PH value of normal soil is 7. 
15. What is an universal indicator?
Ans: An universal indicator is a combination of various types of organic indicators that is used ot find out the strength of acid or base. 
16. What is antacid?
Ans: Antacid is a mild base that are used to neutralize the acidity inside the stomach. Eg. Al(OH)₃, Mg(OH)₂.
17. Which salt is used in plastering of fractured bone?
Ans: Plaster of Paris or Calcium sulphate (CaSo₄) is used in plastering of fractured bones.
18. Write down the name of a basic salt.
Ans: The name of some basic salt are Na₂CO₃, Ca(HCO₃)₂ , CH₃COONa (Sodium acetate). 
19. Name two antacids which are used in treatment of gastric problem in human beings.
Ans: The two antacids which are used in treatment of gastric problem in human beings are Al(OH)₃, Mg(OH)₂.
20. What is the chemical substance in calamine lotion?
Ans: Zinc carbonate is present in calamine lotion.
21. What is Plaster of Paris? Give molecular formula.
Ans: Plaster of Paris is a white powder of calcium sulphate that forms a paste when mixed with water and then thickens and hardens. It s molecular formula is CaSo4
22. Which acid is used as a source of vitamin C?
Ans: Citric acid is used as a source of vitamin C. 
23. Name the alkali without metal.
Ans: NH₄OH (ammonium hydroxide) is a alkali without metal.
24. What is used to reduce hyper acidity in the stomach?
Ans: Milk of magnesia (Mg(OH)₂) is used to reduce hyper acidity in the stomach. 

2 marks questions

1. All alkalis are bases but all bases are not alkalis, justify this statement.
Ans: All alkalis are bases but all bases are not alkalis because some bases are soluble in water and others are insoluble in water. Water soluble bases are called alkali while the bases which are not soluble in water are not alkali. So, all alkalis are base but all bases are not alkali .
2. NaCl is a neutral salt but NaHSo4 is an acidic salt. Give reason.
Ans: NaCl is a neutral salt by NaHSo4 is an acidic salt because NaCl is formed by the complete replacement of H+ ion from acid by sodium ion but in case of NaHSo4 it is formed by the partial replacement of H⁺ ion of acid by sodium ion. So, NaHSo₄ is a acidic salt and NaCl is a neutral salt.  
3. Write any two differences between acid and base.
Ans: The differences between acid and baser are: 

S.no	Base	Alkali
1	Bases are oxide and hydroxide of metals	Water soluble oxides or hydroxide of metals are called alkali.
2	They may or may not be soluble in water.	They dissolve in water to produce hydroxide.
3	Examples: CaO, K2O, CuO etc.	Examples: NaOH, KOH etc.

4. Why HCl is not called organic acid although it is produced inside the human stomach?

Ans: Organic acids are the chemical substance that is produced by animals or plants. Although HCl is produced inside the human body it is not considered as organic acid because an organic acid should contain at least one carbon atom in it but the there is not a single atom of carbon atom in HCl. 

5. What is type of salt is called acidic salt? Write any two examples.
Ans: The salt that contains acidic radical of a strong acid and basic radical  of weak base is called acidic salt or the salt that is formed by the partial replacement of  hydrogen ion from the acid by a base is called acidic salt. Eg: NaHSo₄, KHSo₄, NaHSo₃ etc.  
6. Why acid is called Proton donor?
Ans: Acid is called proton donor because hydrogen present in acid donates the proton to give H⁺ ion when dissolve in water. 
7. Pickles can’t be stored in metal vessels for a long time. Give reason.
Ans: Pickles can't be stored in metal vessels for a long time because pickles contains acid which react with metals to form toxic compound that is harmful to human body causing several health problems.
8. Write two uses of acid in our daily life.
Ans: Two uses of acid in our daily life are:

i. sulphuric acid is used for making chemical fertilizers.

ii. citric acid is the source of vitamin C.

9. Write two application of neutralization reaction.
Ans: Two application of neutralization reaction are: 

i. to control acidity of soil.

ii. it is used in treatment of hyperacidity in human stomach. 

10. Name any two salts that are used in our daily life and also write major uses of each.
Ans: Salts that are used in our daily life are: 

A. sodium chloride(NaCl)

i. it is used in our food as balanced diet.

B. Ammonium chloride (NH₄Cl)

i. it is used as a good electrolyte in dry cells.

11. Why Hydrochloric acid is called strong acid?
Ans: Hydrochloric acid is called strong acid because it have high degree of ionization and produce more hydrogen ions after complete dissociation in aqueous solution. 
12. What will happen when a metal reacts with dilute sulphuric acid?
Ans: When a metal reacts with dilute sulphuric acid it produce hydrogen gas and corresponding salt.

example: Mg+ H₂SO₄ ======> MgSO₄ + H₂

13. What happens when alkali reacts with ammonium salt?
Ans: When alkali reacts with ammonium salt, it decomposes and produces ammonia gas and water. 
14. Write equations to show the reaction between:
a] Hydrochloric acid and potassium hydroxide
b] Sulphuric acid and sodium hydroxide
Ans: a. HCl + KOH ===>KCl +H₂O

         b. H₂SO₄ + 2NaOH ======> Na₂SO₄ + 2H₂O
15. Write down the two uses of Sulphuric acid.
Ans: The two uses of Sulphuric acid are: 

1. It is used for making chemical fertilizers.

2. It is used to extract metals. 

16. Write down the two uses of Nitric acid.
Ans: The two uses of Nitric acid are

i. it is used in preparation of drugs, plastic, fertilizers.

ii. It is used as a chemical doping agent in electrochemistry.

17. Write the equations to represent the reactions of sodium hydroxide (i) with metal (ii) with hydrochloric acid.
Ans: a. with metal: 

        i. NaOH + Zn + H₂O  ====> Na₂ZnO₂ + H₂ ( in aqueous solution)

        ii. NaOH + HCl ======> NaCl +H₂O
18. Write down the two uses of Sodium hydroxide (NaOH).
Ans: The two uses of Sodium hydroxide (NaOH) are:

i. it is used in the manufacture of soaps, paper etc.

ii. it is also used in petroleum products.

19. Write down the two uses of potassium hydroxide (KOH).
Ans: The two uses of potassium hydroxide (KOH) are:

i. it is used in the manufacture of soaps.

ii. it is used for making medicine.

20. An element burns in oxygen to form its oxide which is soluble in water, aqueous solution gives blue colour with red litmus. What conclusion do you get from the given observation?
Ans: When a metal burn in air with oxygen it forms oxide of the metal. If the oxide of metal is placed water it forms the hydroxide of the metal which is a base as it changes the red litmus paper turn into red. It concludes that when oxides of metal is dissolved in water it forms a base. 
21. White residue formed after burning magnesium in air is dissolved in water. What type of solution is formed?
Ans: When magnesium is burnt in air with oxygen it forms magnesium oxide which is white residue. If the white residue is dissolved in water it forms the hydroxide of magnesium which is a base. 
22. Name the acid injected during the ant bite. Which chemical is used to treat it?
Ans: The acid that is injected during ant bite is formic acid or methanoic acid. Different kinds of alkalis are used to treat the bite of ant.  A mild alkali like calamine lotion or sodium hydrogen carbonate  is used to reduce the burning. 
23. The problem of acidity in stomach is treated by taking solution of milk of magnesia. Explain why?
Ans; Mild acid HCl is produced inside our stomach during digestion of food. If sufficient food is not taken in time this acid starts to damage the tissues of stomach that may lead to acidity and gastric problem to neutralize the effect of this acid we use a base called milk of magnesia (Mg(OH)₂). 
24. Which acid is injected when nettle stings? What is its treatment?
Ans: The acid that is injected during nettle sting is formic acid or methanoic acid. Different kinds of alkalis are used to treat the bite of ant.  A mild alkali like calamine lotion or sodium hydrogen carbonate  is used to reduce the burning.
25. What is injected when wasp sting? What is its treatment?
Ans: When wasps sting, a kind of alkali passes in the skin due to which we feel burning sensation. Mild acids like vinegar of acetic acid is used to reduce burning when wasps sting. 
26. NaHSO₄ is an acidic salt, how? Explain with appropriate reason.
Ans: NaHSO₄ is an acidic salt because it is formed by the partial replacement of hydrogen in from acid by sodium ion. When this salt is dissolved in water it produces some amount of hydrogen ions. 

3 marks questions

27. Write any three methods of preparation of salts.
Ans: The three methods of preparation of salts are: 

i. By direct combination of elements. 

Eg: 

ii. By the neutralization of acid and base.

Eg: 

iii. By the action of an acid with carbonates or bicarbonates.

Eg: 
28. How can magnesium ribbon be changed into alkali? Write with chemical reaction.
And: When magnesium is burnt in air with oxygen it forms magnesium oxide which is white residue. If the white residue is dissolved in water it forms the hydroxide of magnesium which is a base. 

MgO + H₂O ======> Mg(OH)₂ 
29. Write three uses of acid.
Ans: The three uses of acid are: 

i. Citric acid is used as the good source of vitamin C.

ii. Nitric acid is used for preparing drugs, dyes, plastics, explosive, fertilizer etc. 

iii. Sulphuric acid is used in industries for the extraction of metals and it is used as electrolyte in car battery. 
30. Write three uses of salt.
Ans: The three uses of salt are:

i. Sodium chloride is used in our food as nutrient. 

iii. Copper sulphate is used for electroplating. 

iv. Sodium bicarbonate is used as baking powder. 
31. Write three uses of base.
i. Sodium hydroxide is used in the manufacture of soap, paper, and the synthetic fiber rayon.

ii. Calcium hydroxide (slaked lime) is used in the manufacture of bleaching powder.

iii. Ammonium hydroxide is used for making chemical fertilizer. 

32. What compounds are formed when acid and base react? Write the name of this reaction. Give one example of it.
Ans: When acid and base react with each other, salt and water is formed. This type of reaction is called acid-base reaction or neutralization reaction because the properties of both acid and base are neutralized by each other and new compounds are formed which are different from them. 
33. Aqueous solution of Na₂CO₃ turns red litmus into blue. Give reason.
Ans: 
34. If a compound gives, H⁺ ion and Cl^- when dissolved in water. Name the compound. What type of compound is it? Give reason.

35. Write down the importance of the following with molecular formula.

i. Sodium chlorine 

ii. Acetic acid

iii. Aluminum hydroxide.

36. What are the types of salts? Define all of them with an example of each.

37. Write down the uses of the following acids:

a. Nitric acid b. Sulphuric acid c. Hydrochloric acid.

38. Write down the uses of the following bases:

a. Sodium hydroxide 

b. Ammonium hydroxide

c. Potassium hydroxide

39. Sodium hydroxide solution reacts with dilute sulphuric acid:

i. What type of substance is sodium hydroxide?

ii. What is this reaction called?

iii. Write a balanced chemical equation for this reaction.

40. Name the acid injected during the ant bite. Which chemical is used to treat it?

41. Name the acid injected during the bee bite. Which chemical is used to treat it?

42. Name the base injected during the wasp bite. Which chemical is used to treat it?

43. Which acid is injected when nettle or ants bite? Which chemical is used to treat it?

44. How many types of salts are there depending upon the PH value? Give examples of each.

45. Write the uses of the following:

a. Zinc sulphate

b. Carbonic acid

c. Ammonium hydroxide

4 marks questions

46. Water is water regarded as acid as well as base, why?

47. With an appropriate example, prove that neutralization is combination of H⁺ of acid with OH^- of base to give water.

48. What are the differences between strong and weak acid. Clarify with examples.

49. What happens when metallic bicarbonate is reacted with dilute hydrochloric acid? Explain with a suitable example.

50. PH value of water is 7 but when a few drops of dilute HCL is added to that water, its PH value drops below 7. Why does it happen so?

51. What is neutralization reaction? Write any three importance of neutralization reaction.

52. How an alkali be made from magnesium ribbon? Write balanced chemical equation as well.

53. Write down the uses of the following:

a. Citric acid

b. Nitric acid

c. Sulphuirc acid

d. Hydrochloric acid

e. Carbonic acid

f. Boric acid

g. Carbolic acid

h. Acetic acid

54. Write down the uses of the following bases:

a. Sodium hydroxide

b. Ammonium hydroxide

c. Calcium hydroxide

d. Magnesium hydroxide

e. Potassium hydroxide

f. Calcium oxide

55. Write down the uses of the following salts:

a. Sodium chloride

b. Calcium sulphate or gypsum

c. Sodium bicarbonate

d. Copper sulphate or blue vitrol

e. Zinc sulphate or white vitrol

f. Ferrous sulphate or green vitrol

g. Iron sulphate

h. Ammonium sulphate

i. Silver nitrate

j. Sodium carbonate

k. Ammonium chloride