Assignment - Acids, Bases & Salts, Class 10, Science PDF Download

Fill in the blanks :

1. An indicator changes its .................with change of the nature of the solution.

2. The properties of.................are due to the hydrogen ions it produces in aqueous solution.

3. A water soluble base produces.................ions in solutions.

4. A farmer treats the soil of his field with lime when the soil has .................nature.

5. Electrolysis of an aqueous solution of .................produces hydrogen at cathode, chlorine at anode and sodium hydroxide in the solution.

6. Hydrated copper sulphate contains five molecules of ...............of crystallization.

7. Phenolphthalein gives a ................ colour when added to sodium hydroxide solution.

8. Blue litmus turns red when added to ................solution.

9. the pH of an acidic solution is ................than 7.

10. NaCl + H₂SO₄ ........... + HCl.

11. 2P + 5H₂SO₄(conc.) .......... + 2H₂O + 5SO₂.

12. 3Fe + 4H₂O .............+ H₂

ANSWER KEY

Fill in the blanks

1. Colour 2. an acid 3. Hydroxide(OH^_) 4. Acidic

5. Sodium chloride 6. Water 7. Pink 8. an acidic

9. Less 10. NaHSO₄ 11. 2H₃PO₄ 12. Fe₃O₄

(A) Very Short Answer Type Questions :

1. Name the acids present in (i) vinegar (ii) lemon (iii) orange

2. Which is a stronger acid and why : HCl or CH₃COOH.

3. Which type of acid forms only the normal salts ?

4. Name the gas which is liberated at cathode during the electrolysis of mineral acid.

5. Write the main use of boric acid.

6. How alkalis differ from bases ? Explain

7. What will happen to the concentration of [H⁺] ions in a solution if NaOH is added to water ?

8. Why does copper not react with dil. H₂SO₄ or dil.HCl ?

9. Name the metals which are soluble only in aqua regia.

10. When concentrated acid is diluted, does the pH get higher or lower ?

(B) Match the following :

1. Column-A  Column-B

Compound                Chemical name

(i) Bleaching powder  (a) Sodium bicarbonate

(ii) Baking soda          (b) Sodium carbonate

(iii) Washing soda       (c) Calcium oxychloride

(iv) Plaster of Paris     (d) Calcium sulphate hemihydrate

Match the following

(i) → (c), (ii) → (a), (iii) → (b), (iv) → (d)

Questions

Q. Why should curd and sour susbtances not kept in brass and copper vessels ? [NCERT]

Q. 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 ? [NCERT]

Q. Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride [NCERT]

Q. Why do HCl, HNO₃, etc show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic characters ? [NCERT]

Q. Why does an aqueous solution of an acid conduct electricity ? [NCERT]

Q. Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids.
Describe an Activity to prove it.

Q. Why does dry HCl gas not change the colour of the dry litmus paper ? [NCERT]

Q. Why does distilled water not conduct electricity, whereas rain water does ? [NCERT]

Q. Why do acids not show acidic behaviour in the absence of water ? [NCERT]

Q. When diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ? [NCERT]

Q. How is the concentration of hydronium ions (H₃O⁺) affected when a soution of an acid is diluted?

[NCERT]

Q. How is the concentration of hydroxide ions (OH^_) affected when excess base is dissoved in a solution of sodium hydroxide ? [NCERT]

Q. You have two solutions, A and B. The pH of solutions A is 6 and pH of solution B is 8. Which
solution has more hydrogen ion concentration ? Which of this is acidic and which one is basic ? [NCERT]

Q. What effect does the concentration of H⁺ (aq) ions have on the nature of the solution ?[NCERT]

Q. Do basic solutions also have H⁺(aq) ions ? If yes, then why are these basic ? [NCERT]

Q. What is the common name of the compound CaOCl₂ ? [NCERT]

Q. Name of the substance which on treatment with chlorine yields bleaching powder. [NCERT]

Q. What will happen if a solution of sodium hydrogen carbonate is heated ? Give the equation of the reaction involved. [NCERT]

Q. Name the sodium compound which is used for softening hard water. [NCERT]

Q. Give two important uses of washing soda and baking soda. [NCERT]

Q. Write an equation to show the reaction between plsater of paris and water. [NCERT]

Q. Plaster of Paris should be stored in a moisture -proof container. Explain why ? [NCERT]

Short Answer Type Questions :

1. How is plaster of paris obtained ? What reaction is involved in the setting of a paste of plaster of paris?

2. What happens when crystals of washing soda are left open in dry air. What is this named as ?

3. How can you prepare acid-base indicator at home ?

4. Write down the molecular formula for : Sulphuric acid, Nitric acid, Phosphric acid, Carbonic acid.

5. Name the gas evolved when dilute sulphuric acid acts as sodium carbonate. Write the chemical equation for the reaction involved.

6. What does pH stand for ? What does a pH scale indicate.

7. Differentaite between :

(i) Strong acid and concentrated acid

(ii) Weak base and dilute base

8. 'Sweet tooth' may lead to tooth decay. Explain why ? What is the role of toothpaste in preventing cavities?

9. A blue salt becomes white on heating. With the help of a reaction explain the change in colour.

10. Why do we not categorise metal oxides as salts while we categorise metal sulphide as salts ?

11. What happen when electric current is passed through brine ? Give reaction.

12. Select the formulae of acids, bases and salts from the following list :

NaCl, NaOH, H₃PO₄, Na₂CO₃, Ca(OH)₂, CuSO₄.5H₂O, H₂SO₄,H₂CO₃ , HCl, NaHCO₃, Na₂CO₃^.10H₂ O, Al(OH)₃, KCl

LONG Answer Type Questions :

1. Dry HCl gas does not affect a dry blue litmus paper, whereas it changes a moist blue litmus paper to red. Explain.

2. What is the pH scale ? How can you know, if the given sample is acidic, basic or neutral from its pH value.

3. How can you classify salts on the basis of their solubility in water ? Give examples.

4. What is plaster of paris ? How is it prepared ? Give the chemical equation.

5. Comment on the statement : Are the crystals of salts really dry ?

6. Discuss chlor-alkali process for manufacturing sodium hydroxide.

ANSWER KEY

Very short answer type

1. (i) Acetic acid (ii) Citric acid (iii) Citric acid 2. HCl, because it ionises completely in dilute aqueous solution 3. Monobasic acids 4. Hydrogen 5. For eye washing and as an antiseptic.

6. All alkalis are water soluble while all bases are not water soluble

7. [OH^_] concentration will increase 8. Copper not a active metal

9. Pt and Au 10. Higher