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Natural Indicators Around Us

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Q: On washing with soap, a turmeric stain on the cloth turns to red becauseA. soap solution is alkaline.B. soap solution is acidic.C. turmeric contains a natural indicator.D. turmeric contain litmus.Select the correct alternative.

Turmeric is a natural indicator.It turns red in basic solution whereas in acidic solution it remains yellow.

Q: You are provided with three test tubes A, B and C which contain distilled water, acidic solution and basic solution respectively. If you are given blue litmus paper only, how will you identify the contents of each test tube.

The given blue litmus paper is dipped in the given solutions. The solution which turns blue litmus red is acidic solution. Now Tear this blue litmus turned red into 2 halves. Now, the solution which turns it blue again is the acidic solution and the one which does not affect it is distilled water.

Q: Which one of the following will turn blue-litmus red?

The liquids turns the litmus paper different colours because one is acid one is base and one is neutral. Litmus paper is an indicator which can identify whether the substance is an acid or base.Vinegar is the diluted form of acetic acid as being acid it will turn blue litmus red.

Q: Which of the following set of substances contain acids only?

Curd contains lactic acid and vinegar contains acetic acid. Lime water, soap, and milk of magnesia are basic substances and grapes contain tartaric acid.

Q: You are provided with three test tubes A, B and C as shown in Figure with different liquids. What will you observe when you puta) A piece of blue litmus paper in each test tube.b) A piece of red litmus paper in each test tube.c) A few drops of phenolphthalein solution to each test tube.

Test tube Effect on blue litmus Effect on red litmus Effect on phenolphthaleinA Changes to red Remains red ColourlessB Remains blue Changes to blue Pink colourC Remains blue Remains blue Colourless

Q: State whether the following statements are true or false. Correct the false statements.Phenolphthalein is a natural indicator.

Phenolphthalein is a man made indicator. It gives pink colour when added to a base. Therefore, it is considered as a base indicator.

Q: Phenolphthalein is a synthetic indicator and its color in acidic and basic solutions, respectively are:

\textbf{Correct answer:} Option (D) \textbf{Explanation:} Phenolphthalein is a synthetic indicator and is weakly acidic in nature. When it is added to an acidic solution, it turns colourless. In the basic solution, it appears pink in colour. \textbf{Conclusion:} Phenolphthalein is colourless in acidic solution and pink in basic solution.

Q: Which of the following is acid-base indicator?

Turmeric is yellow in acidic and neutral solutions; is bright red in basic solutions. Hence, it is an acid-base indicator.

Q: Turmeric is a natural indicator. On adding its paste to acid and base separately, which color would be observed ?

Turmeric is yellow in acidic and neutral solutions; is bright red in basic solutions.

Q: Look at Figure which shows solutions taken in test tubes A,B,C and D. What colour is expected when a piece of red litmus paper is dropped in each test tube?Nature of the solutions is given in the table for your help.TestNature of solutionChange in colour of red litmusANeutralBBasicCAcidicDNeutral

According to the given condition:Test Nature of solution Change in colour of red litmus A Neutral No ChangeB Basic Colour will change to blue C Acidic No changeD Neutral No change

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Important Questions

On washing with soap, a turmeric stain on the cloth turns to red because
A. soap solution is alkaline.
B. soap solution is acidic.
C. turmeric contains a natural indicator.
D. turmeric contain litmus.
Select the correct alternative.

Medium

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You are provided with three test tubes A, B and C which contain distilled water, acidic solution and basic solution respectively. If you are given blue litmus paper only, how will you identify the contents of each test tube.

Medium

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Which one of the following will turn blue-litmus red?

Medium

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Which of the following set of substances contain acids only?

Medium

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You are provided with three test tubes A, B and C as shown in Figure with different liquids. What will you observe when you put
a) A piece of blue litmus paper in each test tube.
b) A piece of red litmus paper in each test tube.
c) A few drops of phenolphthalein solution to each test tube.

Easy

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State whether the following statements are true or false. Correct the false statements.

Phenolphthalein is a natural indicator.

Medium

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Phenolphthalein is a synthetic indicator and its color in acidic and basic solutions, respectively are:

Medium

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Which of the following is acid-base indicator?

Medium

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Turmeric is a natural indicator. On adding its paste to acid and base separately, which color would be observed ?

Medium

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Look at Figure which shows solutions taken in test tubes A,B,C and D. What colour is expected when a piece of red litmus paper is dropped in each test tube?
Nature of the solutions is given in the table for your help.
Test Nature of solution Change in colour of red litmus
A Neutral
B Basic
C Acidic
D Neutral

Medium

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Test	Nature of solution	Change in colour of red litmus
A	Neutral
B	Basic
C	Acidic
D	Neutral