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: In the titration of ferrous ammonium sulphate and potassium dichromate, the external indicator used is:

The solution will turn yellow with addition of dichromate ions and when ferric ions are produced they will also impart a yellow color to the solution so there is no color change during the reaction and you need some other indicator The use of potassium ferricyanide(\$K_3Fe(CN)_6\$ as an external indicator is the best known example in the titration of iron with dichromate. As long as ferrous ion is present in the titration mixture, the indicator will turn blue on the transfer of solution. The appearance of blue colour is due to the formation of ferroferricyanide (Turnbull’s blue) according to flowing.Hence option C is correct.

Question 1

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

Accepted Answer

$\textbf{Correct answer:} $ Option (D)&#65279;$\textbf{Explanation:}$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.&#65279;$\textbf{Conclusion:}$ Phenolphthalein is colourless in acidic solution and pink in basic solution.

Question 2

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.

Accepted Answer

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

Question 3

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

Accepted Answer

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.

Question 4

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.

Accepted Answer

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

Question 5

Which of the following set of substances contain acids only?

Accepted Answer

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

Question 6

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.

Accepted Answer

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.

Question 7

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

Accepted Answer

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

Question 8

In the titration of ferrous ammonium sulphate and potassium dichromate, the external indicator used is:

Accepted Answer

&#10;&#10;The solution will turn yellow with addition of dichromate&#10;ions and when ferric ions are produced they will also impart a yellow color to&#10;the solution so there is no color change during the reaction and you need some&#10;other indicator&#10;&#10;The use of potassium ferricyanide($K_3Fe(CN)_6$ as an external indicator&#10;is the best known example in the titration of iron with dichromate. As long as&#10;ferrous ion is present in the titration mixture, the indicator will turn blue&#10;on the transfer of solution. The appearance of blue colour is due to the&#10;formation of ferroferricyanide (Turnbull&#8217;s blue) according to flowing.Hence option C is correct.&#10;&#10;

Question 9

An organic dye, cousins used to detect the endpoint of precipitation titration by the process of

Accepted Answer

An organic dye, cosine used to detect the endpoint of precipitation titration by adsorption, is called an adsorption indicator. This is also called Argentometry titration. Argentometry is a type of titration involving the silver(I) ion. Typically, it is used to determine the amount of chloride present in a sample. The sample solution is titrated against a solution of silver nitrate of known concentration. Chloride ions react with silver(I) ions to give the insoluble silver chloride:$Ag^+ +Cl^- \longrightarrow AgCl (K=5.88\times 10^9$)The yellow fluorescein is a common example used for the reaction i.e., -  $NaCl (aq) + AgNO_3 (aq)\rightarrow AgCl (s) +NaNO_3 (aq)$

Question 10

An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change?

Accepted Answer

Red litmus is turned to blue by the addition of base or alkali like sodium hydroxide and for reversing this reaction,turning blue litmus to red requires addition of an acid like hydrochloric acid.

Revise with Concepts

Basics of Indicators

Learn with Videos

Quick Summary With Stories

Indicators

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

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.

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

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.

Which of the following set of substances contain acids only?

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.

In the titration of ferrous ammonium sulphate and potassium dichromate, the external indicator used is:

An organic dye, cousins used to detect the endpoint of precipitation titration by the process of

An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change?

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

Revise with Concepts

Basics of Indicators

Learn with Videos

Quick Summary With Stories

Indicators

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

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.

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

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.

Which of the following set of substances contain acids only?

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.

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

In the titration of ferrous ammonium sulphate and potassium dichromate, the external indicator used is:

An organic dye, cousins used to detect the endpoint of precipitation titration by the process of

An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change?

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.

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.