6.4 cm (max) - 25 cm (min)
Her soil is acidic in nature.
From Nakia's test where she obtained a pH value of 4, she can conclude that she is working with an acidic soil.
The soil is mildly acidic and she should be very conscious of the kind of crop to grow in such a place.The pH or pOH scale is convenient scale for measuring the acidity and alkalinity of a soil. It runs from 1 to 14. 1 to 7 is the range of acidity. 7 to 14 is for alkalinity7 is for neutral soils