CBSE Class 10 Science Acids Bases And Salts Worksheet Set 06

This printable Class 10 Science worksheet for Chapter 2, Acids, Bases and Salts, has 23 short questions with answers: fill in the blanks, true or false, matching and one-line questions. It revises indicators, the reactions of acids, the names and formulae of common salts, hydrogen and carbon dioxide tests and the uses of baking soda and bleaching powder.

Fill in the Blanks, True or False and Matching

Question 1. Fill in the blanks:
1. Acids turn _____ litmus to _____.
2. Basic solution of pH is always _____ than 7.
3. Mild base like _____ gives relief on the bee-stung area.
4. _____ is the fixed number of water molecules that is attached chemically to each formula unit of a salt in its crystalline form.
5. The stomach produces too much _____ during indigestion and this causes pain and irritation.
6. _____ are the products formed when bleaching powder reacts with dilute sulphuric acid.
7. The presence of _____ in acids is responsible for their acidic properties.
8. KNO₃ has pH value equal to _____.
9. Among the given acid HCl, H₂SO₄ and CH₃COOH, _____ is a weak acid.
10. _____ is one of the raw materials for the production of baking soda.
Answer:
1. blue, red
2. more (greater)
3. baking soda
4. Water of crystallisation
5. hydrochloric acid (HCl)
6. CaSO₄, Cl₂ and H₂O
7. H⁺ ions
8. 7
9. CH₃COOH
10. Sodium chloride (brine)
In simple words: Ten quick facts on acids, bases and salts.

Teacher's Note:
1. Write only the missing word in each blank.
2. KNO₃ is the salt of a strong acid and a strong base, so it is neutral.

Question 2. Write True or False:
1. Methyl orange indicator gives yellow colour in basic solution.
2. All the organic acids are strong acids.
3. Litmus (indicator) is obtained from nettle plant.
4. The strength of an acid or base is measured on the basis of scale of numbers known as pH scale.
5. Oxalic acid is present in ant sting.
6. The dilution of a concentrated acid is always done by adding concentrated acid to water slowly with stirring.
7. The sodium chloride aqueous solution is acidic in nature.
8. Glucose solution will conduct electricity.
9. Plaster of Paris can be stored in any type of containers.
10. The more alkaline a solution, the more is the pH.
Answer:
1. True.
2. False. Most organic acids, such as acetic acid, are weak acids.
3. False. Litmus is obtained from lichens.
4. True.
5. False. Formic acid is present in ant sting.
6. True.
7. False. Sodium chloride solution is neutral (pH 7).
8. False. Glucose does not form ions in water.
9. False. It must be stored in a moisture-proof container.
10. True.
In simple words: Check each statement against what you know about indicators, pH and salts.

Teacher's Note:
1. Correct each false statement.
2. Write the answers in the space given and check them with this key.

Question 3. Match the following: P. Strong acid, Q. Weak acid, R. Weak base, S. Strong base with 1. H₂SO₄, 2. CH₃COOH, 3. NaOH, 4. NH₄OH.
Answer:
P - 1: strong acid is H₂SO₄
Q - 2: weak acid is CH₃COOH
R - 4: weak base is NH₄OH
S - 3: strong base is NaOH
In simple words: Strong ones ionise completely.

Teacher's Note:
1. Match each type with its example.
2. NH₄OH is a weak base.

Question 4. Match the pH value with the solution: P. 6.5 to 6.7, Q. 7.4, R. 2.4 - 3.4, S. 12.4 with 1. Vinegar, 2. Milk, 3. Human blood, 4. Lime water.
Answer:
P - 2: milk has pH 6.5 to 6.7 (slightly acidic)
Q - 3: human blood has pH 7.4 (slightly basic)
R - 1: vinegar has pH 2.4 to 3.4 (acidic)
S - 4: lime water has pH 12.4 (basic)
In simple words: Compare the pH of everyday substances.

Teacher's Note:
1. Blood is slightly basic.
2. Vinegar is the most acidic here.

Question 5. Match: P. Water is produced, Q. H₃O⁺, R. H₂, S. Carbon dioxide gas with 1. Metal + acid, 2. Acid + Base, 3. Metal carbonate + acid, 4. Acid + water.
Answer:
P - 2: acid + base gives salt and water
Q - 4: acid + water gives H₃O⁺
R - 1: metal + acid gives H₂
S - 3: metal carbonate + acid gives CO₂
In simple words: Link each product with its reaction.

Teacher's Note:
1. Learn the general reactions of acids.
2. Metal carbonate gives CO₂.

Very Short Answer Questions

Question 6. Write the name of the products obtained when zinc metal pieces are dropped into sodium hydroxide bottle.
Answer:
Sodium zincate and hydrogen gas are obtained: Zn(s) + 2NaOH(aq) → Na₂ZnO₂(aq) + H₂(g).
In simple words: Zinc reacts with a strong base to give sodium zincate and hydrogen.

Teacher's Note:
1. Both a metal and a base can give hydrogen here.
2. Name both products.

Question 7. Write an equation for the action of dilute hydrochloric acid on marble chips.
Answer:
Marble chips are calcium carbonate: CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g).
In simple words: Marble gives carbon dioxide with acid.

Teacher's Note:
1. Check that the equation is balanced.
2. The gas turns lime water milky.

Question 8. Write the chemical name and formula of baking soda.
Answer:
Chemical name: sodium hydrogencarbonate (sodium bicarbonate). Formula: NaHCO₃.
In simple words: Baking soda is NaHCO₃.

Teacher's Note:
1. Do not confuse it with washing soda, Na₂CO₃·10H₂O.
2. Learn name and formula together.

Question 9. Name the raw materials required to manufacture bleaching powder.
Answer:
Chlorine gas, Cl₂, and dry slaked lime, Ca(OH)₂.
In simple words: Bleaching powder is made from chlorine and dry slaked lime.

Teacher's Note:
1. Chlorine comes from the chlor-alkali process.
2. Lime must be dry.

Question 10. Write the chemical formula of plaster of paris.
Answer:
CaSO₄·½H₂O (calcium sulphate hemihydrate).
In simple words: POP has half a molecule of water per formula unit.

Teacher's Note:
1. Gypsum is CaSO₄·2H₂O.
2. Plaster of Paris has half a molecule of water: CaSO₄·½H₂O.

Question 11. Show with the help of an equation that metal carbonates liberate carbon dioxide on reaction with dilute acid.
Answer:
Na₂CO₃(s) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + CO₂(g)
In simple words: A carbonate plus an acid gives a salt, water and CO₂.

Teacher's Note:
1. Write the state symbols.
2. Balance chlorine and sodium.

Question 12. What effect does the concentration of H⁺ (aq) have on acidic nature of the solution?
Answer:
The higher the concentration of H⁺(aq) ions, the more acidic the solution; the lower the concentration, the less acidic the solution.
In simple words: More H⁺ means more acidic.

Teacher's Note:
1. pH goes down when H⁺ goes up.
2. This is directly from NCERT.

Question 13. Write the reaction between dilute NaOH solution and dilute HCl acid.
Answer:
NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l). It is a neutralisation reaction.
In simple words: Acid plus base gives salt and water.

Teacher's Note:
1. This is the standard neutralisation equation.
2. Name the type of reaction.

Question 14. Name the products formed from the chlor-alkali process.
Answer:
Sodium hydroxide, chlorine gas and hydrogen gas.
In simple words: Electrolysis of brine gives NaOH, Cl₂ and H₂.

Teacher's Note:
1. Chlorine collects at the anode and hydrogen at the cathode.
2. The name chlor-alkali comes from chlorine and alkali.

Question 15. Name the gas evolved when dilute sulphuric acid acts on sodium carbonate.
Answer:
Carbon dioxide: Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂↑.
In simple words: A carbonate with acid gives CO₂.

Teacher's Note:
1. Test the gas with lime water.
2. Write the equation as well.

Question 16. Write the name and the chemical formula of the organic acid present in vinegar.
Answer:
Acetic acid (ethanoic acid), CH₃COOH.
In simple words: Vinegar contains acetic acid.

Teacher's Note:
1. Vinegar has about 5 to 8 percent acetic acid.
2. It is a weak acid.

Question 17. What is the colour of phenolphthalein in milk of magnesia?
Answer:
Pink, because milk of magnesia is basic (magnesium hydroxide) and phenolphthalein is pink in a base.
In simple words: Phenolphthalein is pink in base.

Teacher's Note:
1. Milk of magnesia is an antacid.
2. Phenolphthalein is colourless in acid.

Question 18. Which acid is present in honey bee sting and hair of nettle leaves?
Answer:
Methanoic acid (formic acid), HCOOH.
In simple words: Both stings contain formic acid.

Teacher's Note:
1. Baking soda gives relief.
2. Ants also release formic acid.

Question 19. What effect does an increase in concentration of H⁺(aq) in a solution have on the pH of solution?
Answer:
The pH of the solution decreases.
In simple words: More H⁺ means lower pH.

Teacher's Note:
1. pH = −log[H⁺].
2. The solution becomes more acidic.

Question 20. How does colour of litmus change in acidic and basic media?
Answer:
In an acidic medium blue litmus turns red, and in a basic medium red litmus turns blue (litmus is red in acid and blue in base).
In simple words: Litmus is red in acid and blue in base.

Teacher's Note:
1. Litmus is a purple dye from lichen.
2. Mention both media.

Question 21. What is the source of litmus?
Answer:
Litmus is obtained from lichens (a plant-like organism), which is why it is called a natural indicator.
In simple words: Litmus comes from lichen.

Teacher's Note:
1. Litmus is a purple dye.
2. It is a natural indicator.

Question 22. Write the name of some natural indicators.
Answer:
Red cabbage leaves, turmeric, litmus, and coloured petals of flowers such as petunia, hydrangea and geranium.
In simple words: Natural indicators come from plants.

Teacher's Note:
1. Name at least two.
2. They change colour in acid and base.

Question 23. Write the name of some synthetic indicators.
Answer:
Phenolphthalein and methyl orange.
In simple words: Synthetic indicators are made in the laboratory.

Teacher's Note:
1. Name two.
2. Phenolphthalein is colourless in acid and pink in base.