Class 10 Science
Chapter 2 Acids, Bases and Salts
Previous years appeared questions
Multiple Choice Questions
1. As the pH value of a neutral solution increases (March 2020)
(A) basic property decreases and number of OH− ions increases
(B) acidic property increases and number of H+ ions decreases
(C) basic property increases and number of OH− ions increases
(D) acidic property decreases and number of H+ ions increases.
Ans. : (C) basic property increases and number of OH− ions increases
2. The chemical equation that represents neutralization reaction among the following is (March 2019, KSEEB MP 22-23)
Ans: C
One Marks Questions
1. Write any two uses of Plaster of Paris. (March 2022)
Ans. :
- Plaster of Paris is used in :
- Supporting fractured bones
- Making toys
- Decorative materials
- Making smooth surfaces. ( Any two )
- Solution A is more acidic.
- As it has more + H ions.
3. Draw the diagram of the arrangement of apparatus showing the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning and label the zinc granules. (Sep 2020)
Ans:
4. Agricultural scientists have suggested to add a certain amount of lime powder to an agricultural field. What may be the reasons for this ? Explain. (March 2020)
Ans. :
> Plants require a specific pH range for their healthy growth.
> Soil of his land is acidic.
> Lime powder is a base.
> So adding lime powder to the soil, decreases the acidic property / soil is neutralised.
5. Draw the diagram of the apparatus to show that acid solution in water conducts electricity. Label the following parts : i) Dil. HCl solution ii) Rubber cork. (March 2020)
Ans:
7. Name the gas liberated when an acid reacts with metallic carbonate. Write the chemical equation of the reaction when this gas is passed through lime water. What is the colour of the precipitate obtained in this reaction ? (June 2019)
Ans:
> When an acid reacts with metallic carbonate , carbon dioxide gas is liberated.
> When carbon dioxide gas is passed through lime water, calcium carbonate is produced as a white precipitate.
> The chemical equation is :
Ca(OH)2 + CO2→ CaCO3 + H2O
8. Give scientific reason :
(i) While diluting an acid, the acid should be added to water.
(ii) Plaster of Paris should be stored in a moisture-proof container. (June 2019)
Ans:
> adding water to a concentrated acid releases a large amount of heat, which can cause an explosion and acid burns on the skin, clothing, and other body parts.
> Plaster of Paris in contact with moisture (water) changes to solid hard mass, gypsum. Therefore, it gets wasted. Hence it should be stored in moisture proof container
9. Draw the diagram of arrangement of apparatus used to show the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the following parts. (i) Soap solution (ii) Delivery tube. (March 2019)
Ans:
10. There is no change in the colour of red litmus and blue litmus paper when introduced into an aqueous solution of sodium chloride. After passing direct current through the same solution, red litmus changes to blue colour. Which product is responsible for this change ? Mention any two uses of this product. (March 2019)
Ans:
Sodium Hydroxide is responsible for this change. Use of this product is:
> Sodium hydroxide is used in drain and oven cleaners
> It is also commonly used in the manufacture of fabric, plastic wrap, paper and soap
11. Write the molecular formula and two uses of each of the following compounds: a) Washing soda b) Bleaching powder (KSEEB MQP 2021)
Ans:
a)
Molecular formula : Na2CO3
Uses:
> used in soap, glass and paper industries.
> It helps in the removal of permanent hardness of the water.
b)
Molecular formula : CaOCl2
Uses
> for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry.
> as an oxidising agent in many chemical industries
> to make drinking water free from germs. ( Any two uses)
12. Name the two gases liberated in Chlor-alkali process. Write one use of each. (KSEEB MQP 2021)
Ans:
two gases liberated in Chlor-alkali process are Hydrogen and Chlorine gas
Uses of chlorine
> It is used in the production of bleaching powder.
Uses of Hydrogen gas
> It is used as fuel for rockets.
13. The gas liberated when sodium carbonate reacts with dilute hydrochloric acid is passed through lime water, a white precipitate is formed. But when the same gas is passed through lime water in excess, precipitate is not visible. Why? (KSEEB MQP 2020)
Ans:
because of formation of calcium hydrogen carbonate. As calcium hydrogen carbonate is soluble in water, thus, the milky colour of solution mixture disappears.
14. While diluting an acid it is recommended that the acid should be added to water and not water to acid. Why? (KREIS MQP - 20)
Ans:
Because adding water to a concentrated acid releases a large amount of heat, which can cause an explosion and acid burns on the skin, clothing, and other body parts. adding acid to water is safe, but adding water to acid is not.
15. List any four importance of pH in everyday life. ( KREIS Midterm 2022)
Ans:
> pH helps in the digestion of food
> Stopping tooth decay,
> Remedy for the acidic effect of honeybee bite.
> Maintaining soil pH
16. What is the common name of the compound CaOCl2? Write any two uses of it. (KREIS Midterm 2022)
Ans:
Common name of the compound CaOCl2 is Bleaching powder
Bleaching powder is used .
> for bleaching cotton and linen in the textile industry ,
> bleaching wood pulp in paper factories and for bleaching washed clothes in laundry ;
> as an oxidising agent in many chemical industries ; and
> to make drinking water free from germs . (Any two)
17. What is the chemical name of bleaching powder ? Write any two uses of it. (KSEEB MQP 22-23)
Ans :
chemical name : Calcium oxy chloride( CaOCl2)
Uses : (i) for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry;
(ii) as an oxidising agent in many chemical industries; and
(iii) to make drinking water free from germs. (Any Two)
18. What is concentrated acid? Name the acid present in the stinging hair of nettle leaves. (KSEEB MQP 22-23)
Ans :
★ Acid with more concentration of H+ /H3O+ ions per unit volume.
★ Methanoic acid
Three Marks questions
1. Draw the diagram of arrangement of the apparatus to show the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the following parts :
i) Zinc granules ii) Soap solution. ( june 2022)
Ans. :
2. a) What is neutralisation reaction ? Give an example.
b) What is the common name of the compound that has molecular formula CaSO4. 1/2 H2O. (june 2022)
Ans. :
a) Reaction between acids and bases to form salt and water is called neutralisation reaction.
OR
Base + Acid → Salt + water.
Ex : NaOH + HCl → NaCl + H2O. [ Consider any suitable example ]
b) Calcium sulphate hemihydrate or Plaster of Paris.
3. Draw the diagram of arrangement of the apparatus to show the reaction of zinc granules with dilute sulphuric acid and testing hydrogen gas by burning. Label the following parts : (March 2022)
i) Zinc granules ii)Delivery tube.
Ans. :
Reaction of zinc granules with dilute sulphuric acid :
4. Write the molecular formulae and two uses of each of the following compounds : a) Bleaching powder b) Plaster of Paris. (Sep 2020)
Ans. :
a)
CaOCl2
Uses
> for bleaching cotton and linen in the textile industry, for bleaching wood pulp in paper factories and for bleaching washed clothes in laundry.
> as an oxidising agent in many chemical industries
> to make drinking water free from germs. ( Any two uses)
b)
CaSO4. 1/2 H2O
Uses
> for making toys
> making materials for decoration
> for making surfaces smooth. ( Any two uses )
5. What is a strong acid ? Explain how tooth decay is caused. How can it be prevented ? (Sep 2020)
Ans:
> Acid that gives rise to more +H ions is said to be strong acid.
> Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating. So the pH in the mouth decreases and the tooth enamel gets corroded.
> Using toothpastes which are generally basic, for cleaning the teeth.
6. Write the molecular formula and any one uses of each of the following compounds. a. Washing soda b. Bleaching powder c. Plaster of Paris. ( KREIS Midterm 2022)
Ans:
a.
Na2CO3
Uses:
used in soap, glass and paper industries
b)
Ca(ClO)₂
Uses:
Used as an oxidising agent in chemical industries
c)
CaSO4.1/2H2O.
Uses:
supporting fractured bones in the right position.
Four Marks Questions
1. (i) What is neutralisation reaction ?
(ii) Name the products of chlor-alkali process. Write one use of each. (June 2019)
Ans:
(i) Neutralization is a type of chemical reaction in which an acid reacts with a base to form salt and water.
(ii) There are three products that are produced in the Chlor-alkali process. These are Sodium Hydroxide (NaOH), chlorine gas (Cl2), and hydrogen gas(H2).
Uses of sodium hydroxide
> It is used in the manufacturing of paper.
Uses of chlorine
> It is used in the production of bleaching powder.
Uses of Hydrogen gas
> It is used as fuel for rockets.
a) Explain the manufacturing of bleaching powder. Write any two uses of it.
b) A strong solution of sodium hydroxide is added to the strong solution of hydrochloric acid. What is the nature of the salt solution formed here ? Write a balanced chemical equation for this reaction.
Ans:
Comment Your Opinion👇
No comments:
Post a Comment