Question 9
Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is
(a) neutral?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration
(a) D
(b) C
(c) B
(d) A
(e) E
Increasing order of hydrogen-ion concentration — C < E < D < A < B
Key Concepts Covered
This question tests your understanding of the following concepts from the chapter Acids, Bases and Salts: Question, Solutions, Tested, Universal, Indicator, Showed. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 10 curriculum.
A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This Question
Read the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to Remember
- Read the question carefully and identify all parts before answering.
- Use the terminology specific to this subject and chapter.
- Review the textbook content for this chapter before attempting questions.
- Practice writing concise, well-structured answers within time limits.
Practice more questions from Acids, Bases and Salts — Science, Class 10 CBSE
Chapter 2: Acids, Bases and Salts — Quick Revision Guide
Introduction
Acids and bases are fundamental chemical substances found everywhere in daily life. This chapter explores their properties, the pH scale, neutralisation reactions, and the preparation of important salts.
Key Points at a Glance
- Acids produce H+ (H3O+) ions in water; bases produce OH− ions
- Indicators: Litmus (red/blue), methyl orange, phenolphthalein, turmeric; olfactory indicators change smell
- Acid reactions: with metals (salt + H2), carbonates (salt + H2O + CO2), metal oxides (salt + H2O), bases (neutralisation)
- pH scale: 0–14; pH < 7 acidic, pH = 7 neutral, pH > 7 basic; measured by universal indicator
- pH importance: stomach (1–2), blood (7.35–7.45), tooth decay below pH 5.5, soil pH for agriculture
- Always add acid to water (dilution is exothermic); dry HCl gas does not affect litmus
- Chlor-alkali process: electrolysis of brine gives NaOH + Cl2 + H2
- Important salts: Bleaching powder (CaOCl2), Baking soda (NaHCO3), Washing soda (Na2CO3·10H2O), Plaster of Paris (CaSO4·½H2O)
- Water of crystallisation: CuSO4·5H2O (blue) loses water on heating → CuSO4 (white)
Real-World Connections
Antacids neutralise excess stomach acid; baking soda makes bread fluffy by releasing CO2; washing soda softens hard water; bleaching powder purifies drinking water; Plaster of Paris is used in fracture casts.
Quick Self-Test (5 Questions)
- What is the most important concept you learned from this chapter?
- Can you write three key equations/formulae from this chapter from memory?
- Draw a labelled diagram relevant to this chapter without looking at your notes.
- Explain one real-world application of a concept from this chapter.
- What is one common mistake students make in this chapter, and how can you avoid it?
Further Study
- NCERT Textbook Chapter 2
- NCERT Exemplar Problems
- Bright Tutorials Detailed Notes: ch02-acids-bases-salts.html
- Bright Tutorials Practice Questions: ch02-acids-bases-salts.html
- Previous Year CBSE Board Papers