Which of the following is used as a measure for the acidity or alkalinity of soil?

Potential of hydrogen or pH is a measure of the acidity or alkalinity of a solution. The pH scale ranges from 0 to 14, with 7 being neutral. Values below 7 indicate increasing acidity, while values above 7 indicate increasing alkalinity. Soil pH is an important factor in crop production because it affects the availability of nutrients to plants and the activity of soil microorganisms.

Electrical conductivity is a measure of the soil's ability to conduct an electrical current. It is often used as an indicator of the soil's salinity, which can affect plant growth.

Organic matter is a measure of the amount of decomposed plant and animal material in the soil. Organic matter is important for soil fertility and structure.

Cation exchange capacity is a measure of the soil's ability to hold onto positively charged ions, such as calcium, magnesium, and potassium. It is an important property of soil because it affects nutrient availability to plants.