Question 1

Q1: A solution turns the red litmus paper to blue. Excess addition of which of the following solution would reverse the change? (i) Lime water (ii) Baking...

Accepted Answer

The correct answer is (iii) Vinegar. Vinegar is an acidic solution. A solution that turns red litmus paper to blue is basic. To reverse the change, an acidic solution needs to be added. Lime water and baking soda are basic, and common salt solution is neutral. Vinegar is the only acidic option.

Question 2

Q10: Three liquids are given to you. One is vinegar, another is a baking soda solution, and the third is a sugar solution. Can you identify them only using...

Accepted Answer

Yes, they can be identified using turmeric paper. 1.  Dip the turmeric paper into each of the three liquids. 2.  Vinegar is acidic, so it will not change the colour of the turmeric paper. 3.  Baking soda solution is basic, so it will turn the turmeric paper red. 4.  Sugar solution is neutral, so it...

Question 3

Q11: The extract of red rose turns the liquid X to green. What will the nature of liquid X be? What will happen when excess of amla juice is added to liqui...

Accepted Answer

The nature of liquid X will be basic. When excess amla juice is added to liquid X, the green colour of the red rose extract will eventually change to red. This is because amla juice is acidic and will neutralize the basic solution, eventually turning it acidic.

Question 4

Q12: Observe and analyse the information given in the following

Accepted Answer

This question is incomplete, as it refers to information that is not included in the provided text. Therefore, it is not possible to provide a solution.

Question 5

Q2: You are provided with three unknown solutions labelled A, B, and C, but you do not know which of these are acidic, basic, or neutral. Upon adding a fe...

Accepted Answer

The correct answer is (iv) Basic, basic, and basic. Solution A turns red litmus blue, indicating it is basic. Solution B turns turmeric solution red, indicating it is basic. Solution C turns red rose extract green, indicating it is basic.

Question 6

Q3: Observe and analyse Figs. 2.13, 2.14, and 2.15, in which red rose extract paper strips are used. Label the nature of solutions present in each of the...

Accepted Answer

Based on the chapter content: Fig. 2.13: The red rose extract paper strip is red, indicating the solution is acidic. Fig. 2.14: The red rose extract paper strip is unchanged (red rose extract colour), indicating the solution is neutral. Fig. 2.15: The red rose extract paper strip is green, indicatin...

Question 7

Q4: A liquid sample from the laboratory was tested using various indicators: \begin{tabular}{|l|l|l|l|}\hline Indicator & Red litmus & Blue litmus & Turme...

Accepted Answer

The liquid sample is acidic. Justification: Red litmus showed no change, which means it is not basic. Blue litmus turned red, which is a characteristic of acidic solutions. Turmeric showed no change, which is expected for acidic or neutral solutions. Since blue litmus turned red, it confirms the sol...

Question 8

Q5: Manya is blindfolded. She is given two unknown solutions to test and determine whether they are acidic or basic. Which indicator should Manya use to t...

Accepted Answer

Manya should use an olfactory indicator. Olfactory indicators are substances whose odour changes in acidic or basic media. Since Manya is blindfolded, she cannot rely on visual indicators like litmus paper or red rose extract. Olfactory indicators like onion or vanilla extract would allow her to dif...

Question 9

Q6: Could you suggest various materials which can be used for writing the message on the white sheet of paper (given at the beginning of the chapter) and...

Accepted Answer

One possibility is to use a turmeric solution for the spraying liquid and a soap solution for writing on the paper. | Writing Material | Spray Bottle Contents | Colour of Writing | |---|---|---| | Soap solution | Turmeric solution | Red | | Baking soda solution | Turmeric solution | Red | | Vinegar...

Question 10

Q7: Grape juice was mixed with red rose extract; the mixture got a tint of red colour. What will happen if baking soda is added to this mixture? Justify y...

Accepted Answer

If baking soda is added to the mixture of grape juice and red rose extract, the mixture will turn green.  Justification: Grape juice is acidic, so the red rose extract will give a red tint. Baking soda is basic. Adding a base to an acidic solution containing red rose extract will cause the extract t...

Question 11

Q8: Keerthi wrote a secret message to her grandmother on her birthday using orange juice. Can you assist her grandmother in revealing the message? Which i...

Accepted Answer

To reveal the message written with orange juice, the grandmother can use turmeric paper as an indicator. Orange juice is acidic. The message can be revealed by spraying a basic solution, like soap solution, over the paper. The turmeric paper will turn red where it comes into contact with the basic s...

Question 12

Q9: How can natural indicators be prepared? Explain by giving an example.

Accepted Answer

Natural indicators can be prepared from substances found in nature, such as flowers, vegetables, and spices. These indicators change colour in the presence of acidic or basic substances. Example: Red rose extract can be prepared by crushing red rose petals and immersing them in hot water. The water...

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