B. Answer Briefly 1. Differentiate between acidic and basic substances. 2. What are indicators? Give examples. 3. Window cleaning solution contains ammonium hydroxide. When a drop of this solution is put on red litmus paper, it turns blue. Explain. 4. Why do you need indicators? 5. How is China rose indicator prepared? 6. Sodium chloride salt is used for cooking. It is formed when hydrochloric acid is added to sodium hydroxide solution, both of which are corrosive in nature. But sodium chloride is not. Give reasons. 7. Why does a vegetable stain turn reddish-brown when washed with soap solution? 8. You are provided with a solution which is bitter in taste and soapy to touch. It is used to manu- facture soap. What will happen if a drop of methyl orange is added to it? 9. What is the chemical nature of distilled water?
Chapter - Different kinds of materials
Class - 7
Answers
Explanation:
Turmeric solution turns red in contact with bases and is not affected by acids and neutral substances. Put one drop of each liquid as the turmeric paper. The liquid whose drop turns the paper red is solution hydroxide (base).
Now, this red turmeric paper may be used to identify which one of the remaining two liquids is hydrochloric acid. Put one drop of each of these remaining liquid on the red turmeric paper. The liquid whose drop will turn this red paper yellow is hydrochloric acid. This colour changes from red to yellow because hydrochloric acid neutralizes the pH effect of sodium hydroxide on turmeric paper.
There is no effect on turmeric solution by sugar solution.
Answer:
acid - acid is sour in taste and very corrosive in nature
base-it is bitter in taste and slippeey to touch
indicators are substance that help us to check the substance is acidic or basic