Question

A student was given three solution marked X, Y, and Z, and asked to arrange them in the increasing order of their pH values. The student put two drops of each solution on three strips of universal indicator paper separately. The colours shown by the three indicator strips are as follows:

Which of the following gives the correct increasing order of pH values ?
(1) Z < X < Y
(2) Y < Z < X
(3) X < Y < Z
​(4) Z < Y < X

Answer 1

A universal indicator shows red to yellow colour for acids, and blue to indigo shows base. So, when a student puts drops of X with universal indicator gives blue colour, so it is a base, Y with universal indicator gives yellow colour, so it is an acid, Z with universal indicator gives the green colour, so it is neutral. So, by the variation in the colour of pH paper, we can arrange them in increasing order: Y < Z < X.

Hence, the correct answer is option 2.