Give three examples of endoparasites of cattle. (ii) Enumerate two methods of controlling pests of cattle. 5. (b) (i) What is a formula mass of a compound? (ii) An atom Q has 12 neutrons and 11 pr

Mass number = Number of protons + Number of neutrons  
Mass number = $11 + 12 = 23$  
The mass number is $\boxed{23}$.

• (β) write its electron configuration;

The electron configuration is $\boxed{1s^2 2s^2 2p^6 3s^1}$.

• (γ) what type of ion will Q form in a compound. Atom Q has 1 electron in its outermost shell (3s¹). It will tend to lose this electron to achieve a stable octet configuration. Therefore, Q will form a positive ion with a charge of +1 (a cation).

5. (c) (i) State two ways by which humans could be protected from harmful effects of radioactivity.

• Limiting exposure time to radioactive sources.
• Increasing distance from radioactive sources.
• Using shielding materials (e.g., lead, concrete) between humans and radioactive sources.

5. (c) (ii) Give three uses of radioisotopes.

• Medical diagnosis and treatment (e.g., Iodine-131 for thyroid disorders, Cobalt-60 for cancer therapy).
• Sterilization of medical equipment and food products.
• Carbon dating to determine the age of archaeological artifacts.
• Industrial gauging (e.g., measuring thickness of materials).

5. (d) State five effects of climate change on humans.

• Increased frequency and intensity of extreme weather events (e.g., heatwaves, floods, droughts), leading to loss of life and property.
• Food insecurity due to disrupted agricultural patterns and reduced crop yields.
• Spread of vector-borne diseases (e.g., malaria, dengue fever) as warmer temperatures expand vector habitats.
• Displacement and migration of populations due to rising sea levels and uninhabitable regions.
• Impacts on mental health due to stress, anxiety, and trauma from environmental disasters and uncertainty.

6. (a) (i) What are alkanoates?
Alkanoates are a class of organic compounds also known as esters, formed from the reaction between an alkanoic acid (carboxylic acid) and an alcohol. They typically have the general formula RCOOR', where R and R' are alkyl groups.

6. (a) (ii) State three uses of alkanoates?

• Used as flavorings and fragrances in food, perfumes, and cosmetics due to their pleasant fruity smells.
• Used as solvents for paints, varnishes, and glues.
• Used in the production of polymers (e.g., polyesters).

6. (b) (i) Explain the term weathering.
Weathering is the process of breaking down rocks, soil, and minerals as well as wood and artificial materials through contact with the Earth's atmosphere, biota, and waters. It can be physical (mechanical), chemical, or biological.

6. (b) (ii) State three ways of maintaining soil fertility on a sloppy land.

• Terracing: Creating level steps or platforms on slopes to reduce water runoff and soil erosion.
• Contour ploughing: Ploughing parallel to the contours of the slope to create ridges that slow down water flow.
• Cover cropping: Planting vegetation to cover the soil surface, protecting it from erosion and adding organic matter.
• Strip cropping: Alternating strips of different crops (e.g., row crops with close-growing crops) along the contours.

6. (c) (i) Give two reasons why genetic variation is important in living organisms.

• Enhances adaptability: Genetic variation allows populations to adapt to changing environmental conditions, increasing their chances of survival.
• Drives evolution: It provides the raw material for natural selection, leading to the evolution of new species and traits.
• Increases disease resistance: A diverse gene pool can make a population more resilient to diseases, as some individuals may possess resistance.

6. (c) (ii) Give three examples of genetic variations in humans.

• Eye color (e.g., blue, brown, green).
• Blood type (e.g., A, B, AB, O).
• Hair color and texture.
• Height.
• Susceptibility to certain diseases.

6. (d) (i) State Archimedes principle.
Archimedes' principle states that the buoyant force (upthrust) on an object submerged in a fluid is equal to the weight of the fluid displaced by the object.

**6. (d) (ii) A boat of volume $200 \, \text{m}^3$ floats on sea water of density $10