Bissoy.com
Doctors Medicines MCQs Q&A

There are three test tubes A, B and C, all having colorless liquid of equal volume and strength. A drop of Phenolphthalein is added to each of them. It is observed that test tubes A and B remain colorless while C becomes pink. When the pink solution of C is added to A and B, it is observed that A remains colorless but B attains pink color. Which of the following is correct inference?

There are three test tubes A, B and C, all having colorless liquid of equal volume and strength. A drop of Phenolphthalein is added to each of them. It is observed that test tubes A and B remain colorless while C becomes pink. When the pink solution of C is added to A and B, it is observed that A remains colorless but B attains pink color. Which of the following is correct inference? Correct Answer <span style="">A =</span><span style=""> Strong Acid </span><span style="">B =</span><span style=""> Weak Acid </span><span style="">C =</span><span style=""> Strong Base</span>

Concept:

  • A strong acid is an acid that is completely ionized in water to produce hydronium ions. The conjugate base of the acid is very weak as it does not react with water at all.
  • A strong base is an acid that is completely ionized in water to produce OH-. The conjugate acid is very weak as it does not react with water at all.
  • A weak acid and base is an acid that partially reacts with water to produce hydronium and hydroxide ions respectively and the conjugate base and conjugate base and acid both are weak.

Explanation:

  • Phenolphthalein is an acid-base indicator and it changes color in pH ranges between 8.3 to 10. In acidic solution, it appears colorless and in basic solution, it turns pink in color.
  • In test tube A throughout the acid-base titration, the solution remains colorless after adding phenolphthalein. Thus, it is a strong acid.
  • In test tube B, first, the solution remains colorless but after adding pink colorless, then the solution becomes pink. Thus, it is a weak acid.
  • In test tube C, the solution become pink after adding the phenolphthalein indicator. Thus, it is a strong base.

Therefore, from the above discussion, it is clear that the correct answer is A = Strong Acid B = Weak Acid C = Strong Base.

Related Questions

Girls in a shopping mall like dresses of three different colors; Red, Blue, and Black. 45% of total girls like red color dress, out of which 60% like only red color. If 36 girls like red color dress along with at least one more color, 10% like both red and blue color while 60% of total girls like black color dress, then how many girls like black color or blue or both color dress but not red color?
In a group, 22 women like Red color, 20 women like the blue color and 19 women like Yellow color. Among them, 5 women like both Red and Blue color, 5 women like both Yellow and Blue color and 9 women like both Red and Yellow color. 14 women like only Blue color and 4 women all the three colors. Find the total number of women who like only Red color.
Samples A, B, C and D are tested for their nature using turmeric and Phenolphthalein and the following observations are recorded. A- turns reddish-brown on adding turmeric B- turns pink on adding Phenolphthalein C- turns yellow on adding turmeric D- remains colourless on adding Phenolphthalein What can be concluded about the nature of A, B, C and D?
The following picture shows the color preferences of a group of girls. The circle represents the pink color, the triangle represents the blue color and the rectangle represents the white color. Which group of girls like blue or pink color but not the white color?
A 60% spirit solution is mixed with r% spirit solution in the ratio 1 : 3 such that a s% spirit solution is obtained. When a (s/3)% spirit solution is mixed with 55% spirit solution in equal ratio, an (r/2)% spirit solution is obtained. Which of the following can be determined? (A) Value of ‘r’ (B) Value of ‘s’ (C) Volume of the 60% spirit solution mixed initially (D) If 9 liters of r% spirit solution was mixed initially, what was the volume of the s% spirit solution thus obtained?
Suppose you have four test tubes labelled as 'A', 'B', 'C' and 'D', 'A' contains plain water, 'B' contains the solution of alkali, 'C' contains the solution of an acid, and 'D' contains the solution of sodium chloride. Which one of these solutions will turn phenolphthalein solution pink?
A chemical solution appears green when the salt concentration is 8 grams per litre (gpl) and red when it is 10 gpl. Pure water was added to the solution of 1 litre of 15 gpl solution till it turned green. Then 125 ml of the green solution is taken out and x grams of salt is added to the green solution to make it red. Another 500 ml of the final solution was taken out and y litres of green solution is added to get a resultant solution of concentration 9.6 gpl.  Assume adding salt doesn’t change its volume and find the ratio of x and y. 
Seven people A, B, C, D, E, F and G live on separate floors of a 7-floor building. Ground floor is numbered 1, first floor is numbered. 2 and so on until the topmost floor is numbered 7. Each one of these having a different cars-Cadillac, Ambassador, Fiat, Maruti, Mercedes, Bedford and Fargo but not necessarily in the same order. Only three people live above the floor on which A lives. Only one person lives between A and the one having a car Cadillac. F lives immediately below the one having a car Bedford. The one having a car Bedford lives on an even-numbered floor. Only three people live between the ones having a car Cadillac and Maruti. E lives immediately above C. E is not having a car Maruti. Only two people live between B and the one having a car Fargo. The one having a car Fargo lives below the floor on which B lives. The one having a car Fiat does not live immediately above D or immediately below B. D does not live immediately above or immediately below A. G does not have a car Ambassador. Question : How many people live between the floors on which D and the one having a car Bedford ?
You have two test tubes 'A' and 'B'. Test tube 'A' contains paste of turmeric whereas test tube 'B' contains aqueous solution of phenolphthalein. On adding a few drops of dilute hydrochloric acid to these test tubes the contents of:
Each question presents a situation and asks you to make a judgement regarding that particular circumstance. Choose an answer based on given information. Himanshu and his two friends were walking on the footpath along the road. Suddenly a car drove by and hit a man, who was crossing the road. Each of them remembers certain number of the 6-digit number plate. All three of them went to police station to file a complaint. When asked about the plate number each of them remembers different numbers. 1. All three confirmed that first two numbers from the left was 35. 2. All three agrees than 4th number from the left was 7. 3. All three agrees that there was no even number in the number plate. 4. All three agrees that two numbers were same. Which of the following would be most likely the number of the number plate?