(ii) At atom Q has 12 neutrons and 11 protons:

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

• (b) write its electron configuration.

Atom Q has 11 protons, so it has 11 electrons.

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

• (c) what type of ion will Q form in a compound.

To achieve a stable electron configuration (octet rule), it will tend to lose this electron.

Atom Q will form a $\boxed{\text{cation with a +1 charge}}$.

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

• Limiting the time of exposure to radioactive sources.
• Increasing the distance from radioactive sources.
• Using appropriate shielding materials like lead or concrete.

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

• Medical diagnosis and imaging (e.g., using Technetium-99m to scan organs).
• Cancer treatment (radiotherapy, e.g., using Cobalt-60).
• Sterilization of medical equipment or food products.

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

• Increased frequency and intensity of extreme weather events (e.g., floods, droughts, heatwaves).
• Rising sea levels leading to displacement of coastal populations and loss of land.
• Impacts on food security due to changes in agricultural yields and crop failures.
• Spread of vector-borne diseases (e.g., malaria, dengue fever) as their habitats expand.
• Increased water scarcity in some regions due to altered precipitation patterns.

6. (a) (i) What are alkanoates?
Alkanoates are organic compounds that belong to the ester functional group. They are derived from alkanoic acids (carboxylic acids) and alcohols, characterized by the -COO- linkage.

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

• Used as flavorings and fragrances in food, beverages, and perfumes due to their pleasant fruity smells.
• Serve as solvents in various industries, such as in paints, varnishes, and glues.
• Used as plasticizers to improve the flexibility and workability of plastics.

6. (b) (i) Explain the term weathering.
Weathering is the process by which rocks, soil, and minerals are broken down or dissolved on the Earth's surface. It can occur through physical, chemical, or biological means, leading to the disintegration and decomposition of materials.

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

• Contour plowing: Plowing across the slope rather than up and down to reduce water runoff and soil erosion.
• Terracing: Constructing level platforms or steps on slopes to create flat areas for cultivation, preventing soil and water loss.
• Cover cropping: Planting non-cash crops (cover crops) to protect the soil surface from the impact of rain and wind, reducing erosion and adding organic matter.

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

• Genetic variation provides the raw material for natural selection, allowing populations to adapt to changing environmental conditions and increasing their chances of survival.
• It contributes to the diversity within a species, which can lead to the evolution of new traits and species over time.

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

• Eye color (e.g., blue, brown, green).
• Blood types (e.g., A, B, AB, O).
• Hair color and texture (e.g., straight, curly, blonde, black).

6. (d) (i) State Archimedes principle.
Archimedes' principle states that when an object is wholly or partially immersed in a fluid, it experiences an upward buoyant force (upthrust) that is equal to the weight of the fluid displaced by the object.

6. (d) (ii) A boat of volume 200 m³ floats on sea water of density 10.30 kg m⁻³. Calculate the upthrust of the sea water on the boat. [g = 10 m s⁻²]

• Volume of displaced water ($V$) = $200 \text{ m}^3$ (since the boat floats, the volume of displaced water is equal to the submerged volume of the boat).
• Density of sea water ($\rho$) = $10.30 \text{ kg m}^{-3}$ (Note: This density value is unusually low for sea water, which is typically around $1025-1030 \text{ kg m}^{-3}$. We will proceed with the given value).
• Acceleration due to gravity ($g$) = $10 \text{ m s}^{-2}$

The upthrust of the sea water on the boat is $\boxed{20600 \text{ N}}$.