Hydrangeas are flowers that have different colors depending on the pH of the soil in which they grow. Helen wants to change the color of her flowers. To do so, she must
increase the pH of her soil from 5.2 to 6,6. She has compost made from vegetable
and fruit peels, coffee grounds and tea bags. She also has a bag of lime. Which
should she use? Describe the type of reaction that will occur.