CBSE Class 10 Chemistry Acids Bases And Salts Worksheet Set B

Question. The acid present in tomato is-
(a) Lactic acid
(b) Oxalic acid
(c) Tartaric acid
(d) Methanoic acid

Answer: B

Question. Rain is called acid rain when its:
(a) pH falls below 7
(b) pH falls below 6
(c) pH falls below 5.6
(d) pH is above 7

Answer: C

Question. Sodium carbonate is a basic salt because it is a salt of a
(a) strong acid and strong base
(b) weak acid and weak base
(c) strong acid and weak base
(d) weak acid and strong base

Answer: D

Question. One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is
(a) hydrochloric acid
(b) tartaric acid
(c) acetic acid
(d) sulphuric acid

Answer: B

Question. When you clean a metal vessel with tamarind the reaction taking place is:
Metaloxide + X--------→ Salt + Water. What is X here?
(a) Acid
(b) Base
(c) Hydrogen
(d) Carbon dioxide

Answer: A

Question. The pH of a solution is 7. How can you increase its pH?
(a) By adding a small amount of acid
(b) By adding a small amount of base.
(c) By adding a small amount of salt.
(d) By passing carbon dioxide gas through it.

Answer: B

Question. Which gas is evolved when acids react with metals?
(a) O₂
(b) CO₂
(c) H₂
(d) N₂

Answer: C

Question. Calcium carbonate reacts with hydrochloric acid to form X, Y ,Z. What areX, Y, Z ?
(a) X:Ca(OH)₂,Y:H₂O,Z:CO₂
(b) X:CaCl₂,Y:H₂O, Z:CO₂
(c) X:Ca(OH)₂,Y:H₂O,Z:H₂
(d) X:CaCl₂,Y:H₂O,Z:H₂

Answer: B

Question. What is gastric acid present in the stomach composed of?
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Nitric acid
(d) Lactic acid

Answer: A

Question. Nettle sting is a natural source of which acid?
(a) Methanoic acid
(b) Lactic acid
(c) Citric acid
(d) Tartaric acid

Answer: A

CASE STUDY BASED QUESTIONS:

1. Read the following and answer the questions :
There are many substances which are used to detect the solutions as acidic or basic. They are called Acid-Base indicators. Depending upon the property of the indicator, we have
different groups of Acid-Base indicators. Some indicators show different colors in acidic or basic medium and some indicators give different odors in acidic and basic medium. These
indicators are either extracted from the plants or synthesized in the laboratory or industry.

Question. Which one of the following can be used as an acid-base indicator by visually impaired student?
(a) Turmeric
(b) Hibiscus
(c) Vanilla
(d) Litmus

Answer: C

Question. Select the incorrect option. 

Answer: B

Question. Which of the following are olfactory indicators?
(a) Onion Extract 
(b) Vanilla Extract
(c) Clove Oil
(d) All are correct

Answer: B

Question. Which of the following will turn red litmus blue?
(a) Amla juice
(b) Soft drink
(c) lemon juice
(d) Baking soda

Answer: D

Question. A solution turns blue litmus red, the pH of the solution is likely to be
(a) 6
(b) 7
(c) 8
(d) 9

Answer: A

2. Read the following and answer the questions :
Taj mahal, the seventh wonder of the world, is made of white stone. This white stone contains the same substance ‘A’ that is present in chalk powder and lime-stone. It is turning
yellow due to polluted air. If it is cleaned by an acidic cleaner, a gas ‘B’ is released, which
when passed through a solution ‘C’, forms the same substance which is present in the white
stone that was used to make Taj mahal.

Question. Solution C is-
(a) CaCl₂
(b) B. CaCO₃
(c) Ca(OH)₂
(d) CaSO₄

Answer: C

Question. The polluted air around Taj mahal leads to the following problem because of which it is getting Marble cancer:
(a) Global Warming
(b) Acid Rain
(c) Green House Effect
(d) All are correct

Answer: B

Question. What is the nature of the substance A?
(a) Acidic
(b) Basic
(c) Neutral
(d) None

Answer: B

Question. The substance A is-
(a) Ca3CO₂
(b) CaCO₃
(c) Ca(OH)₂
(d) CaSO₄

Answer: B

Question. Gas B is-
(a) Hydrogen
(b) Nitrogen
(c) Chlorine
(d) Carbon di oxide

Answer: D

3. Read the following and answer the questions :
A scale for measuring hydrogen ion concentration in a solution, called pH scale has been developed. The p in pH stands for ‘potenz’ in German, meaning power. On the pH scale we can measure pH from 0 to 14. pH should be thought of simply as a number which indicates the acidic or basic nature of a solution. Higher the hydronium ion concentration, lower is the Ph value.

Question. A basic solution could have a pH of-
(a) 3
(b) 5
(c) 7
(d) 9

Answer: B

Question. The table provides the pH of four solutions P, Q, R and S:

Which of the following correctly represents the solutions in increasing order of their hydronium ion concentration?
(a) P> Q>R >S
(b) P>S >Q >R
(c) S<Q <R <P
(d) S< P < Q<R

Answer: C

Question. If the pH of any solution is 13, then the color obtained on adding universal indicator to it will be:
(a) Red
(b) Orange
(c) Green
(d) Purple

Answer: D

Question. Which one of the following will have the highest hydrogen ion concentration?
(a) pH=1.1
(b) pH = 2.2
(c) pH =3.3
(d) pH =4.4

Answer: A

Question. How is the hydrogen ion concentration and pH related to each other?
(a) They are inversely proportional.
(b) They are directly proportional.
(c) They are equal.
(d) They have no relation.

Answer: D

4. Read the following and answer the questions :
The Ph value of any solution is a number which simply represents the acidity and basicity of that solution. The pH value of any solution is numerically equal to the logarithm of the inverse of the hydrogen ion(H⁺) concentration.

Question. The nature of toothpaste is:
(a) Neutral
(b) Acidic
(c) Basic
(d) Can be acidic or basic

Answer: C

Question. If a solution gives dark blue color and water is added to it, its color will become:
(a) Dark blue
(b) Red
(c) Light blue to green
(d) Purple

Answer: C

Question. Universal indicator strip gives green colur when put in our mouth before eating food. This indicates that:
(a) The pH of saliva is basic in nature
(b) The pH of saliva is near neutral
(c) Saliva is acidic in nature
(d) All are in correct

Answer: A

Question. The pH value for distilled water would be:
(a) 5
(b) 6
(c) 7
(d) 10

Answer: C

Question. Using above picture can you predict the colour of Ph paper when dipped in limejuice:
(a) Dark Red
(b) Light Orange
(c) Green
(d) Blue

Answer: D

5. Read the following and answer the questions :
Water of crystallization is the fixed number of water molecules present in one formula unit of a salt. Water of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. A salt with associated water of crystallization is known as a hydrate.

Question. The formula of Plaster of Paris is CaSO4. ½ H₂O, it is to be noted that half water molecule is shown to be attached as water of crystallization. This indicates that
(a) Only half water molecule is present in Calcium Sulphate crystal
(b) Two formula units of Calcium Sulphate share one molecule of water.
(c) Two formula units of calcium Sulphate share two molecules of water
(d) Two formula units of Calcium Sulphate share one and a half molecules of water.

Answer: B

Question. Given below are some chemicals. Select the one that have 7 molecules of water attached in hydrated form:
(a) Blue vitriol
(b) Green Vitriol
(c) POP
(d) Washing Soda

Answer: B

Question. When blue vitriol is heated its color changes from:
(a) White to Blue `
(b) Blue to White
(c) White to Green
(d) Blue to Green

Answer: B

Question. Which of the following salt does not contain water of crystallisation?
(a) Blue Vitriol
(b) Baking Soda
(c) Washing soda
(d) Gypsum

Answer: B

Question. The temperature at which Gypsum (CaSO₄. 2H₂O) into Plaster of Paris (CaSO₄.1/2 H₂O
(a) 373K
(b) 273K
(c) 374K
(d) 430K

Answer: A
 

Very Short Answers Type Questions

Question. A teacher provided acetic acid, water, lemon juice, aqueous solution of sodium hydrogen carbonate and sodium hydroxide to students in the school laboratory to determine the pH values of these substances using pH papers. One of the students reported the pH values of the given substances as 3, 12, 4, 8 and 14 respectively. Which one of these values is not correct ? Write its correct value stating the reason.
Answer : The value of pH for water is not correct. The correct value of pH of water is 7 because it has almost equal concentration of H+ and OH– due to which it is neutral.

Question. What is observed when a pinch of sodium hydrogen carbonate is added to 2 ml of acetic acid taken in a test tube ? Write chemical equation for the reaction involved in this case.
Answer : CO₂ gas is evolved with brisk effervescence when sodium hydrogen carbonate is added to acetic acid.
NaHCO₃       +        CH₃COOH CH₃COONa   + H₂O + CO₂
Sodium hydrogen    Acetic acid     Sodium
carobonate acetate

Question.Blue litmus solution is added to two test tubes A and B containing dilute HCl and NaOH solution respectively. In which test tube a colour change will be observed ? State the colour change and give its reason. 
Answer : Test tube A will show colour change because acids turn blue litmus to red. So the final colour of test tube would be red.

Question. What is observed when 2 ml of dilute hydrochloric acid is added to 1 g of sodium carbonate taken in a clean and dry test tube ? Write chemical equation for the reaction involved.
Answer : A brisk effervescence would be observed if HCl is
added to Na₂CO₃ due to the evolution of CO₂ gas.
Na₂ CO₃ + HCl → NaCl + H₂O + CO₂.

Question. A gas is liberated immediately with a brisk effervescence, when you add acetic acid to sodium hydrogen carbonate powder in a test tube. Name the gas and describe the test that confirms the identity of the gas. 
Answer :
CH₃COOH + NaHCO₃ → CH3COONa + CO₂ + H₂O
Gas evolved is CO₂. It is tested by passing CO₂ in lime water which turns milky due to formation of insoluble CaCO₃.
Ca(OH)₂ + CO₂ → CaCO₃↓ + H₂O

Question. Name one animal and one plant whose stings contain formic acid (or methanoic acid). 
Answer : Animal that contains formic acid–ant. Plant that contains formic acid–nettle plant.

Question. If someone is suffering from the problem of acidity after overeating, which of the following would you suggest as remedy ? Lemon juice, Vinegar, Baking soda solution. Give reason for your choice. 
Answer : Baking soda solution. The solution being basic in nature, it neutralises excess acid in the stomach.

Question.How is the neutralisation of a carbonate with an acid different from the neutralisation of an oxide or a hydroxide ? 
Answer : Neutralisation of a carbonate with an acid produces carbon dioxide gas but not with an oxide or hydroxide.

Question. Why do acids not show acidic behaviour in the absence of water ?
Answer : Acids do not show acidic behaviour in the absence of water because the dissociation of hydrogen ions from an acid occurs in the presence of water only. It is the hydrogen ions that are responsible for the acidic behaviour.

Question. On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green.
(a) Predict the new compound formed which imparts a blue-green colour to solution.
(b) Write a balanced chemical equation of the reaction which takes place.
(c) On the basis of the above reaction, what can you say about the nature of copper oxide ?
Answer :
(a) The new compound formed is Copper (II) chloride,CuCl₂.
(b) CuO(s) + 2HCl(aq) → CuCl₂(aq) + H₂O(l)
(c) Copper oxide is basic in nature.

Question. A substance X which is used as an antacid reacts with dilute hydrochloric acid to produce a gas Y which is used in one type of fire-extinguisher. Name the substance X and gas Y. Write a balanced equation for the chemical reaction which takes place.
Answer : Substance X is sodium hydrogen carbonate; gas Y is
carbon dioxide.
NaHCO₃ + HCl → NaCl + CO₂ + H₂O

Question. (a) Why is it wrong to treat a bee sting with vinegar ?
(b) Why is it wrong to treat a wasp sting with baking soda solution ?
Answer :
(a) Bee injects acid into the skin. Vinegar is acetic acid so it can’t be used to treat bee sting.
(b) Since baking soda is basic in nature so it can’t be used to treat wasp sting because wasp injects alkaline liquid into the skin.

Question. What happens when phenolphthalein is added to an acidic solution ?
Answer : There is no change in colour as it remains colourless.

Question. In the laboratory of a school, the sample of hard water is not available “to study the comparative cleaning capacity of a sample of soap in soft and hard water”.
Which salt from the laboratory can be added to tap water to make it hard ? In the experiment how is cleaning capacity of soap compared ?
Answer :
(a) Sulphate, chloride or hydrogen carbonate of calcium or magnesium can be added to tap water to make it hard.
(b) By adding equal amount of soap to water taken in two test tubes, shaking vigorously and comparing the length of lather or foam formed in each test tube. The cleaning capacity of soap is compared.

Short Answers Type Questions

Question. Complete and balance the following chemical equations : 
(i) NaOH(aq) + Zn(s) →
(ii) CaCO₃(s) + H₂O(l) + CO₂(g) →
(iii) HCl(aq) + H₂O(l) →
Answer :
(i) 2NaOH + Zn    550º C→    Na₂ZnO₂ + H₂
(ii) Calcium carbonate will react with water that is saturated with carbon dioxide to form the soluble calcium bicarbonate.
CaCO₃(s) + CO₂ (g) + H₂O (l) → Ca (HCO₃)₂(aq)
(iii) HCl + H₂O → H₃O+ + Cl–

Question. (a) While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid ?
(b) Dry hydrogen chloride gas does not change the colour of dry litmus paper why ? 
Answer :
(a) The process of mixing the concentrated acid with water is highly exothermic. So, when a concentrated acid is added to water then heat is easily absorbed by the large amount of water. Thus it is recommended to add acid to water and not water to the acid.
(b) Dry hydrogen chloried does not contain any hydrogen ions in it, so it does not show acidic behaviour and thus does not change the colour of dry litmus paper.

Question. How is sodium hydroxide manufactured in industries? Name the process. In this process a gas X is formed as by-product. This gas reacts with lime water to give a compound Y, which is used as a bleaching agent in the chemical industry. Identify X and Y and write the chemical equation of the reaction involved.
Answer : Sodium hydroxide is manufactured by the electrolysis of concentrated aqueous solution of sodium chloride.
                                      Electricity
2NaCl(aq.)   +   2H₂O(l)     →
                                    (Electrolysis)

Sodium chloride   Water
                          (Brine)
2NaOH(aq.)    +    Cl₂(g)      +   H₂(g)
Sodium hydroxide   Chloride     Hydrogen
(Caustic Soda)

The process of manufacture of sodium hydroxide by electrolysis process is called chlor-alkali process.
Gas X is chlorine gas and compound Y is calcium oxychloride (Bleaching powder)
Cl₂(g)    +    Ca(OH)₂  →  CaOCl₂ + H₂O
Chlorine    Lime water     Calcium
gas (X)                       oxychloride (Y)

Question. What would a student report nearly after 30 minutes of placing duly cleaned strips of aluminium, copper, iron and zinc in freshly prepared iron sulphate solution taken in four beakers ? 
Answer : Aluminium displaces the iron from iron sulphate and the colour of two solution changes from green to colourless.
No change takes place when copper strip is dipped in iron sulphate solution.
No change will be observed when iron strips are dipped in iron sulphate solution.
The colour of the solution changes from green to colourless when zinc is added to iron sulphate solution.

1. What are the symptoms of the problem of acidity? What possible remedy can be used at home?

2. Name three chemical indicators.

3. How does turmeric change its colour in an alkaline medium?

4. Write equations for the reaction of an acid with;

  (a) a metal (b) a metal carbonate (c) a metal hydrogencarbonate (d) a base (e) a metallic oxide.

5. On keeping curd in a brass vessel for sometime, it becomes bitter. Why?

6. What happens when an acid is dissolved in water?

7. Why is HCl gas unable to change the colour of a dry blue litmus paper? What happens if the litmus paper is moistened?

8. A solution of HCl in water conducts electricity but that of glucose in water does not. Why?

9. What is a hydronium ion? How is it formed?

10. Which ions are generated by bases in water?

11. For diluting an acid, the acid should be poured carefully in water and not the reverse. Why?

12. When an acid is mixed with water, what happens to:-

  (a) The conc. of hydronium ions per unit volume. (b) The conc. of hydroxide ions per unit volume.

13. Two solutions A & B have pH 2 and 6 respectively. Which is more acidic?

14. Name the hardest chemical substance present in our body.

15. How does acid rain water affect the survival of aquatic life?

16. Why does bee-sting cause pain and irritation? What relief can be given in such a case immediately?

17. From the following, pick the acidic, basic or neutral salts:- (a) Sodium chloride (b) Sodium acetate (c) Ammonium chloride (d) Calcium carbonate (e) sodium carbonate

18. What is chlor-alkali process?

19. How is baking soda & washing soda manufactured?

20. Explain the role of baking soda in baking powder.

21. What is meant by water of crystallization?

22. How can you show with an activity the presence of water in blue copper Sulphate crystals?

23. How is gypsum different from plaster of paris chemically?

24. Why should POP be stored in air tight containers?

25. Write 2 uses of: Washing soda, baking soda. bleaching powder.