Explain endoparasites of cattle, pest control methods, and calculate the mass number, electron configuration, and ion type of an atom.

Mass number = Number of protons + Number of neutrons

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

b) Write its electron configuration.

For a neutral atom, the number of electrons is equal to the number of protons.
Number of electrons = 11

The electron configuration is $1s^2 2s^2 2p^6 3s^1$.

c) What type of ion will Q form in a compound?

The atom has 1 electron in its outermost shell ($3s^1$).

It is easier for the atom to lose 1 electron to achieve a stable electron configuration (like Neon, $1s^2 2s^2 2p^6$) than to gain 7 electrons.

When it loses 1 electron, it forms a positive ion with a charge of $+1$. This is a cation.

5.c)

i) Two ways by which humans could be protected from harmful effects of radioactivity:

• Shielding: Using materials like lead, concrete, or thick water barriers to absorb radiation.
• Distance: Increasing the distance from the radioactive source, as radiation intensity decreases with distance.
• Time: Minimizing the time spent near a radioactive source.

ii) Three uses of radioisotopes:

• Medical diagnosis (e.g., using Technetium-99m for imaging organs) and cancer treatment (e.g., using Cobalt-60 or Iodine-131).
• Carbon dating to determine the age of ancient artifacts and fossils.
• Industrial tracers to detect leaks in pipes or monitor fluid flow.
• Sterilization of medical equipment or food products.

5.d)
Five effects of climate change on humans:

• Increased frequency and intensity of extreme weather events (e.g., heatwaves, floods, droughts, storms), leading to loss of life and property.
• Food insecurity due to changes in agricultural yields, water scarcity, and desertification.
• Spread of diseases as warmer temperatures expand the range of disease vectors (e.g., mosquitoes carrying malaria or dengue).
• Displacement and migration of populations due to rising sea levels, extreme weather, and resource scarcity.
• Impacts on human health such as respiratory problems from air pollution, heat stress, and mental health issues from environmental disasters.

6.a)

i) Alkanoates are a class of organic compounds that are esters derived from an alkanoic acid (carboxylic acid) and an alcohol. They contain the functional group $-COO-$.

ii) Three uses of alkanoates:

• Used as flavoring agents in food and beverages (e.g., ethyl ethanoate for fruity flavors).
• Used as solvents in industries (e.g., ethyl ethanoate in nail polish removers, paints).
• Used in the perfume industry due to their pleasant, often fruity, aromas.

6.b)

i) 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, chemical, or biological.

ii) 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 plowing: Plowing parallel to the contours of the land, which creates ridges that slow down water flow and prevent soil erosion.
• Cover cropping: Planting non-cash crops (cover crops) to protect the soil from erosion, add organic matter, and improve soil structure.
• Strip cropping: Planting different crops in alternating strips along the contours of the slope to reduce erosion.

6.c)

i) Two reasons why genetic variation is important in living organisms:

• Adaptation: It provides the raw material for natural selection, allowing populations to adapt to changing environmental conditions and survive.
• Evolution: It drives evolutionary change, leading to the development of new species over time.
• Disease resistance: A diverse gene pool increases the likelihood that some individuals will have resistance to new diseases, protecting the population.

ii) Three examples of genetic variations in humans:

• Eye color (e.g., blue, brown, green)
• Blood type (e.g., A, B, AB, O)
• Hair color (e.g., black, brown, blonde, red)
• Height
• Skin color

6.d)

i) Archimedes' principle states that any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

ii) A boat of volume $200 \text{ m}^3$ floats on sea water of density $1030 \text{ kg m}^{-3}$. Calculate the upthrust of the sea water on the boat. [$g = 10 \text{ m s}^{-2}$]

Volume of the boat ($V_{boat}$) = $200 \text{ m}^3$
Density of sea water ($\rho_{water}$) = $1030 \text{ kg m}^{-3}$
Acceleration due to gravity ($g$) = $10 \text{ m s}^{-2}$

According to Archimedes' principle, upthrust ($F_B$) = $\rho_{water} \times V_{displaced} \times g$.
Since the boat