1. Identify the following solutions, whether they are acid or base.
| Solution | Change in Indicator | Acid / Base |
| 1. | Phenolphthalein: No change | Acid (Phenolphthalein is colorless in acids) |
| 2. | Methyl Orange: Orange turns red | Acid (Methyl orange turns red in acidic solutions) |
| 3. | Litmus: Red litmus turns blue | Base (Bases turn red litmus paper blue) |
2. Write chemical names from given formulae.
- H₂SO₄ – Sulphuric acid
- Ca(OH)₂ – Calcium hydroxide
- HCl – Hydrochloric acid
- NaOH – Sodium hydroxide
- KOH – Potassium hydroxide
- NH₄OH – Ammonium hydroxide
3. Sulphuric acid has highest importance in chemical Industry. Why?
Answer: Sulphuric acid (H₂SO₄) is called the “king of chemicals” because it is used in making a huge number of other products. It is crucial in:
- Making fertilizers (like superphosphate and ammonium sulphate).
- Processing metals (like steel and copper).
- Making chemicals, dyes, and paints.
- Producing batteries (car batteries).
- Refining petroleum and other oils.
Because it is needed in so many key industries, it is the most important chemical.
4. Give answers.
a. Which acid is used for getting chloride salt?
Answer: Hydrochloric acid (HCl) is used to make chloride salts.
b. By squizzing lemon on a piece of rock the gas liberated turned lime water milky. which compound is present in the rock?
Answer: The rock contains a carbonate compound (like calcium carbonate). Lemon juice (acid) reacts with carbonate to produce carbon dioxide gas, which turns lime water milky.
c. The label on the bottle of chemical is spoiled. How will you find whether the chemical is acidic or not?
Answer: Use a natural indicator. Put a drop of the chemical on turmeric paper. If the yellow stain turns red-brown, it is acidic. You can also use blue litmus paper; if it turns red, the chemical is acidic.
5. Answer the following questions.
a. Explain the difference between acid and base.
| Property | Acid | Base |
| Taste | Sour (e.g., lemon) | Bitter (e.g., baking soda) |
| Touch | – | Soapy/slippery feel |
| Litmus Test | Turns blue litmus red | Turns red litmus blue |
| Ions in Water | Releases H⁺ (hydrogen ions) | Releases OH⁻ (hydroxide ions) |
b. Why indicator does not get affected by salt?
Answer: Indicators change color based on the concentration of H⁺ or OH⁻ ions. Most salts are formed by the neutralization of an acid and a base, so they are neutral and do not release a significant amount of H⁺ or OH⁻ ions in water. Therefore, they do not change the color of acid-base indicators.
c. Which substances are produced by neutralization process ?
Answer: A neutralization reaction between an acid and a base produces a Salt and Water.
Acid + Base → Salt + Water
d. Which are the industrial uses of acids?
Answer:
- Sulphuric Acid: Fertilizers, car batteries, dyes, chemicals.
- Nitric Acid: Fertilizers, explosives, plastics.
- Hydrochloric Acid: Cleaning metals, making PVC plastic, food processing.
- Citric Acid: Food preservative and flavoring in drinks and sweets.
- Acetic Acid: Making vinegar, textiles, plastics.
6. Select proper word given in bracket and fill in the blanks.
(hydrogen, strong, weak, hydroxyl)
a. Main constituent of acid is………..
Answer. Main constituent of acid is hydrogen.
b. Main constituent of base is _____
Answer. Main constituent of base is hydroxyl.
c. Tartaric acid is a …………. acid.
Answer. Tartaric acid is a weak acid.
7. Match the pairs.
| Group A | Group B |
| 1. Tamarind | a. Acetic acid |
| 2.Curd | b. Citric acid |
| 3.Lemon | c. Tartaric acid |
| 4.Vinegar | d. Lactic acid |
- Tamarind | c. Tartaric acid
- Curd | d. Lactic acid
- Lemon | b. Citric acid
- Vinegar | a. Acetic acid
8. State true or false.
a. Oxides of metals are acidic in nature. False (Metal oxides are basic in nature.)
b. Table salt is acidic. False (Table salt (NaCl) is neutral.)
c. Metal corrodes due to salts. True (Salts can speed up the corrosion of metals.)
d. Salts are neutral. False (Salts can be neutral, acidic, or basic depending on the acid and base they come from.)
9. Classify following substances into acidic, basic and neutral group.
Acidic: HCl, H₂SO₄, HNO₃
Basic: MgO, CaO, Na₂CO₃
Neutral: NaCl, KCl, H₂O