Question

On adding a few drops of universal indicator to three unknown colourless solutions (P), (Q) and (R) taken separately in three test tubes shown in the following diagrams, a student observed the changes in colour as green in (P), red in (Q) and violet in (R).The Decreasing order of pH of the solutions taken
a) P> Q > R
b) R > P> Q
c) Q > P> R
d) R > Q > P​

Answer 1

Answer:

answer is : (b) R> P> Q.

It is so because the colourless solution in test tube Q is acidic since universal indicator changes its colour to red when added to acid; the solution in test tube P is neutral since it's colour changed to green and the last test tube contains base as it becomes Violet. Hence, the pH value of acid is the least, neutral solution has comparatively more pH value and base has the maximum pH value.

Answer 2

Answer:

pH is measured using indicator solution by putting a few drops of universal indicator to dilute HCl when the color appears is red. This is compared with pH chart colour which indicates that HCl is a strong acid with pH less than 7.

Explanation:

b) R > P> Q