Answer: a. alkaline b. sulphur
Step-by-step explanation:
A pH is an indicator of acidity and alkalinity nature of a solution. The acidic solutions have low pH value and the basic solutions have high pH value. Some solutions are neither acidic nor basic they are called as neutral (pH = 7). Below the value of 7 the solution is considered to be acidic and above 7 considered to be basic.
According to the given situation, the pH value of 7.6 indicates that the soil is alkaline in nature. Adding sulfur to the soil will lower the pH of the soil. The soil bacteria in the soil will convert the sulfur into sulfuric acid. The accumulation of sulfuric acid in the soil will lower the pH of the soil. As, the plants growing in the alkaline soil are subjected to yellowing of the leaves and chlorosis.