A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue?

(A) Lemon juice

(B) Vinegar

(C) Common salt

(D) An antacid


Universal Indicator-Teachoo.jpg


  • Yellowish-orange color indicates that the soil is slightly acidic .
  • In order to change the color to greenish blue, we add a base so that the pH is increased .


Among the following options, 

  • Lemon juice and vinegar are acidic, 
  • common salt is neutral and
  •   antacid is basic.


So, the correct option is (d) an antacid

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo