Question

2. What is an indicator?
3. Name three substances that we use as
indicators.
4. A few drops of purple cabbage juice are
added to the colourless solution of a salt.
The resulting solution becomes light purple.
What does it indicate about the nature of
the salt?
Does a neutralisation reaction always result
in the formation of a neutral salt?
6. Why are factory effluents harmful to aquatic
organisms?
Long answer questions
E. Answer in detail.
1. You are given three materials in the form
of solutions-citric acid, magnesium
hydroxide and sodium sulphate. Describe
how you will classify the substances
as acidic, basic and neutral using
purple cabbage solution.
2. An acidic substance is mixed with an
equivalent amount of a basic substance.
(1) What is the reaction called?
(ii) What are the products formed?
(iii) Is there any absorption or release of
energy?
(iv) Under what conditions is the product
formed: (a) neutral? (b) basic?
(c) acidic?
3. Write a short note on strong and weak
acids.
4. Describe the properties of bases. Name two
bases and their uses.
5. What is neutralisation? What decides
the nature of a salt formed during a
neutralisation reaction?
6. Farmers sometimes sprinkle white lime
powder in their fields. How does this help?
70​

Answer 1

Answer:

(2) Indicators are substances whose solutions change color due to changes in pH.

(3) Litmus, phenolphthalein, and methyl orange are all indicators that are commonly used in the laboratory.

(6) Some effluents pollute because substances in them enter into a chemical reaction with salts already dissolved in the water. ... Some suspended solids can also cause harmful effects when soluble toxic components present in them are dissolved into the water by biological or chemical action.

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