(i) Nitric acid turns red litmus blue.
(ii) Sodium hydroxide turns blue litmus red.
(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water.
(iv) Indicator is a substance which shows different colours in acidic and basic solutions.
(v) Tooth decay is caused by the presence of a base.
(vi) If an indicator changes colour with a base, it does not change colour with an acid.
Q.2. Fill in the blanks.
(i) Change of colour in an acid and a base depends on the type of the ____.
(ii) Acid turns ____ litmus red.
(iii) Bases turn ___ litmus blue.
(iv) Litmus has a ____ colour in distilled water.
(v) In neutralisation reaction a new substance is formed. This is called ____.
(vi) Lemon juice is ____ in nature.
Q.3. Why curd, lemon juice, orange juice and vinegar taste sour?
Q.4. Tom rubs a solution between fingers and feels soapy, what is the nature of that solution?
Q.5. What do you mean by neutral solution? Give examples.
Q.6. How does rain become acidic?
Q.7. State few properties of acids.
Q.8. Which acid is present in an ant sting?
Q.9. What is the nature of distilled water?
Q.10. Where does the word acid come from?
Q.11. Which is the most commonly used natural indicator?
Q.12. Name the acid which is present in each cell of our body.
Q.13. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Q.14. Is the distilled water acidic/basic/neutral? How would you verify it?
Q.15. Why factory waste is neutralised before disposing it into the water bodies?
Q.16. What is acid rain?
Q.17. What is the role of hydrochloric acid in the stomach?
Q.18. Hydrochloric acid (HCl) helps us to digest food.
Q.19. What is the effect of the China rose indicator on acidic and basic solutions?
Q.20. Why a turmeric stain on my white shirt is turned to red when it is washed with soap.
|1. What are acids, bases and salts?|
|2. Can you give examples of acids, bases and salts?|
|3. How do acids and bases react with each other to form salts?|
|4. What are the common uses of acids, bases, and salts?|
|5. How do acids, bases, and salts affect our daily lives?|