Acids, Bases, and Salts
PART-A Unit-I: General Science
Previous Year Questions (PYQ) for this topic
Every TNPSC question asked from this topic, compiled as a PDF. · PDF 3.4 MB
Acids, Bases and Salts - PYQ Points
1. Properties of Acids
- Ions: Acids produce H+ ions in aqueous solution.
- Litmus Test: Acids turn blue litmus paper red (e.g., HCl, Oxalic acid, Sulphuric acid). This is called qualitative analysis.
- Phenolphthalein: In an acidic medium, phenolphthalein is colorless.
- Displaceable Hydrogen: All acids contain replaceable hydrogen atoms. Though acetic acid has four hydrogen atoms, only one can be replaced (ionizable).
2. pH & Buffer Solution
• Buffer Solution: Used to maintain the pH value of a solution constant.
• pH Calculation: At 25°C, if the pH of a solution is 8, then its pOH value is 6 (since pH + pOH = 14).
• pH Calculation: At 25°C, if the pH of a solution is 8, then its pOH value is 6 (since pH + pOH = 14).
3. Uses and Types of Acids
| Acid | Property / Use |
|---|---|
| Arsenic Acid | Used as a desiccant herbicide. |
| Oxalic Acid | Used to remove iron stains from quartz crystals. |
| Formic Acid | Has the ability to reduce Tollen's reagent. |
| Acetic Acid | A weak acid. |
4. Bases & Salts
- Source of Basicity: In nature, rocks are the main source of basic substances (carbonates, bicarbonates, hydroxides).
- Conjugate Acid/Base: A weak base has a
Free preview ends here