20 extra questions from Class 10 Science – Chapter: Acids, Bases and Salts, with answers (as per NCERT/CBSE syllabus):
🔹 Very Short Answer Questions (1 Mark)
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Q: What is the chemical formula of baking soda?
A: NaHCO₃ -
Q: Name the acid present in lemon.
A: Citric acid -
Q: What is the pH range of acids?
A: Less than 7 -
Q: Which acid is used in car batteries?
A: Sulphuric acid (H₂SO₄) -
Q: What is formed when an acid reacts with a base?
A: Salt and water -
Q: Which gas is released when an acid reacts with a metal?
A: Hydrogen gas (H₂) -
Q: What is the colour change of methyl orange in an acid?
A: Red -
Q: Name one strong acid and one weak acid.
A: Strong acid – HCl; Weak acid – CH₃COOH (acetic acid) -
Q: What is the chemical formula of washing soda?
A: Na₂CO₃·10H₂O -
Q: Write the IUPAC name of NaOH.
A: Sodium hydroxide
🔹 Short Answer Questions (2 Marks)
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Q: Why does dry HCl gas not change the colour of dry litmus paper?
A: Because HCl gas does not release H⁺ ions without water. Acids show acidic behavior only in aqueous solution. -
Q: What happens when zinc reacts with dilute sulphuric acid? Write the balanced chemical equation.
A: Zinc reacts with dilute H₂SO₄ to form zinc sulphate and hydrogen gas.
Equation: Zn + H₂SO₄ → ZnSO₄ + H₂↑ -
Q: Explain why aqueous solution of an acid conducts electricity.
A: Because acids ionise in water to produce free H⁺ ions, which carry current. -
Q: What is meant by neutralisation reaction? Give one example.
A: A reaction between an acid and a base to form salt and water.
Example: HCl + NaOH → NaCl + H₂O -
Q: Define universal indicator. What is its use?
A: A universal indicator is a mixture of indicators that shows different colours at different pH levels. It is used to determine the pH of a solution.
🔹 Application-Based/Conceptual Questions
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Q: A solution has pH = 3. Is it acidic or basic? What colour will blue litmus show in it?
A: Acidic; Blue litmus will turn red. -
Q: Why do acids not show acidic behaviour in the absence of water?
A: Because acids release H⁺ ions only in aqueous solution. Without water, ionisation does not occur. -
Q: How is common salt obtained from sea water?
A: By the process of evaporation (solar evaporation of seawater). -
Q: Write the chemical equation for the preparation of bleaching powder.
A:
Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O -
Q: Why is it advised not to touch acid with bare hands even if it is a weak acid like acetic acid?
A: Because it can still cause skin irritation or burns due to its corrosive nature.
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