Give four reasons why farmers should be discouraged from using chemical fertilizers. What is temporary hard water and write a chemical equation for its softening by heating. What is a lever?

Here are the answers to question 2:

2. (a) Give four reasons why farmers should be discouraged from using chemical fertilizers.

• Chemical fertilizers can lead to soil acidification, reducing soil fertility over time.
• They can cause water pollution through runoff, leading to eutrophication in water bodies.
• Excessive use can harm beneficial soil microorganisms, disrupting the natural soil ecosystem.
• They can contribute to greenhouse gas emissions, particularly nitrous oxide, impacting climate change.

2. (b) (i) What is temporary hard water?
Temporary hard water is water that contains dissolved bicarbonates of calcium and magnesium. It can be softened by boiling, which precipitates these minerals out of the solution.

2. (b) (ii) Write a chemical equation to show how temporary hard water can be softened by heating.
When temporary hard water containing calcium bicarbonate is heated, the calcium bicarbonate decomposes to form insoluble calcium carbonate, carbon dioxide, and water.

$$\mathrm{Ca(HCO_3)_2(aq)} \xrightarrow{\text{heat}} \mathrm{CaCO_3(s) + H_2O(l) + CO_2(g)}$$

2. (c) (i) What is a lever?
A lever is a simple machine consisting of a rigid bar that pivots around a fixed point called a fulcrum, used to multiply force or change the direction of force.

2. (c) (ii) Explain each of the following terms as applied to simple machines:

• (α) mechanical advantage (MA): Mechanical advantage is the ratio of the output force (load) to the input force (effort). It indicates how much a machine multiplies the force applied to it. $$\text{MA} = \frac{\text{Load}}{\text{Effort}}$$
• (β) velocity ratio (VR): Velocity ratio is the ratio of the distance moved by the effort to the distance moved by the load in the same time. It is a theoretical value that depends only on the dimensions of the machine. $$\text{VR} = \frac{\text{Distance moved by effort}}{\text{Distance moved by load}}$$

2. (d) (i) What is food processing?
Food processing is the transformation of raw ingredients into food, or of food into other forms, through physical or chemical means. It involves various techniques to prepare food for consumption, storage, or further use.

2. (d) (ii) State:

• (α) two advantages of food processing;
  • Increases shelf life and reduces spoilage, making food available for longer periods.
  • Enhances food safety by eliminating harmful microorganisms and toxins.
• (β) one disadvantage of food processing.
  • Can lead to a loss of nutrients (e.g., vitamins, minerals) during processing.