Answers section

Questions 4.4.7 (a)

What is the role of fertilizers?
Why has the use of fertilizers become more necessary today than in the past?
Why are some fertilizers classified as nitrogenous?
What are the essential elements for the growth of plants, including crops?
Why is ammonia suitable as a raw material for the manufacture of nitrogenous fertilizers?
The chemical formula of urea, a nitogenous fertilizer, is (NH₂)₂CO. Which of the nitrogenous fertilizers in the pictures above is not a salt? Explain your choice.

Answers to Questions 4.4.7 (a)

To increase crop yield.
Growing population and increasing demand for food call for increased production (yield). With frequent use, the soil has become low in nutrients/exhausted.
They provide nitrogen as the main element to plants.
Nitrogen, phosphorus, potassium.
It consists of nitrogen in a form that can be chemically transformed to fertilizers.
Urea. It does not have metallic ion such as NH₄⁺ ions and negative ions such as NO₃^-, SO₄^2-, CO₃^2-, HCO₃^-, and PO₄^3- that characterize salts.