Activity 2.12 NCERT Class 10 Science, Chapter 2 Acids, Bases, and Salts
Activity 2.12 asks us to collect a soil sample dilute it and check the filtrate with PH paper.
Filtrate changes the colour of filter paper to green.
A PH of normal soil ranges from 5.5 to 7.5. In this ranger PH paper show green.
Soil PH is an important factor in the growth of the plant. Most of the plants grow in the PH range of 5 to 7.5, adjusting the PH of soil result in the optimum output from the plant. For example, plants like apple, cauliflower, cucumber etc. grow in this PH range.
Phosphate fertilizer increases the acidity of the soil while potassium fertilizer neutralizes the PH.
See also: PH of common substances, Activity 2.11.