Draw 3 diagrams to show how particles are mangled in each of the 3 states of matter.

$$
m = 20 \text{ kg}
$$
The mass of the metallic ball is $\boxed{20 \text{ kg}}$.

Q6 (Hoe Safety):

• Give two safety precautions to consider when using a hoe:
  • Always wear appropriate protective footwear to prevent injury to the feet.
  • Ensure the hoe handle is securely attached to the blade to prevent it from detaching during use.

Q7 (Agricultural Tools):

• Outline 4 proper ways of handling agricultural tools:
  • Clean tools thoroughly after each use to remove soil and debris, preventing rust and corrosion.
  • Sharpen cutting edges regularly to maintain efficiency and reduce the effort required for tasks.
  • Store tools in a dry, secure place, preferably hung or with blades covered, to prevent damage and accidents.
  • Oil or grease metal parts periodically to protect them from rust, especially during storage.

Q8 (Housefly):

• Identify 4 breeding places of housefly:
  • Decaying organic matter (e.g., rotting food, garbage)
  • Animal manure
  • Compost piles
  • Sewage and refuse dumps
• Name two diseases transmitted by the housefly:
  • Cholera
  • Typhoid fever

Q9 (Desert Animals):

• Identify two characteristics of animals found in desert:
  • Nocturnal activity: Many desert animals are active at night to avoid the extreme heat of the day.
  • Water conservation: They have adaptations like concentrated urine, dry feces, or the ability to obtain water from food to minimize water loss.

Q10 (Landforms):

• State two ways in which land forms are important to life:
  • Provide habitats: Mountains, valleys, plains, and coastlines offer diverse environments for a wide range of plant and animal species.
  • Influence climate and resources: Landforms affect weather patterns, rainfall distribution, and the availability of natural resources like minerals and water.

Q11 (Metals/Non-metals):

• State 3 uses each of metals and non-metals:
  • Metals:
    • Copper: Used in electrical wiring due to its high conductivity.
    • Iron/Steel: Used in construction for buildings and bridges due to its strength.
    • Aluminum: Used in aircraft and beverage cans due to its light weight and corrosion resistance.
  • Non-metals:
    • Oxygen: Essential for respiration in living organisms and combustion.
    • Carbon: Used in various forms, such as graphite in pencils and diamond in cutting tools.
    • Chlorine: Used as a disinfectant in water treatment and swimming pools.

Q12 (Energy Changes):

• Describe the energy changes that take place when: (The question is incomplete, but typically asks about a specific process. For example, if it were "burning a candle", the answer would be: Chemical energy stored in the wax is converted into light energy and heat energy.)

Section B (Right Column)

Q1 (Stomach Digestion):

• Explain two ways in which the stomach aids in digestion:
  • Mechanical Digestion: The muscular walls of the stomach churn and mix food with gastric juices, breaking it down into smaller pieces.
  • Chemical Digestion: The stomach secretes gastric juice containing hydrochloric acid (which denatures proteins and kills bacteria) and pepsin (an enzyme that begins protein digestion).

Q2 (Poultry):

• Give two uses of poultry:
  • Source of meat (e.g., chicken, duck, turkey) for human consumption.
  • Source of eggs for human consumption.

Q3 (Ruminants):

• State two characteristics of ruminants:
  • They possess a four-chambered stomach (rumen, reticulum, omasum, abomasum) adapted for digesting fibrous plant material.
  • They chew cud, which involves regurgitating partially digested food from the rumen and re-chewing it to further break down plant fibers.

Q4 (Farming Systems):

• Explain the difference between the following farming systems:
  • a) Land rotation and shifting cultivation:
    • Land rotation: Involves growing different crops in sequence on the same piece of land over several seasons to maintain soil fertility and control pests. The land itself remains in continuous use.
    • Shifting cultivation: Farmers clear a plot of land, cultivate it for a few years until soil fertility declines, then abandon it and move to a new plot. The abandoned land is left to regenerate naturally.
  • b) Monoculture and mixed cropping:
    • Monoculture: The practice of growing a single crop species on a large area of land year after year.
    • Mixed cropping: The practice of growing two or more different crop species simultaneously on the same piece of land.
  • c) Monocropping and mixed farming:
    • Monocropping: Similar to monoculture, it involves growing the same crop on the same land repeatedly.
    • Mixed farming: An agricultural system that combines both crop cultivation and the raising of livestock on the same farm.

Q5 (Ecosystem Preservation):

• State three reasons why the ecosystem must be preserved:
  • Biodiversity maintenance: Preserving ecosystems protects the vast array of species, which is crucial for ecological stability and resilience.
  • Ecosystem services: Healthy ecosystems provide essential services like clean air and water, pollination, soil formation, and climate regulation.
  • Resource sustainability: Ensures the continued availability of natural resources for future generations, supporting human well-being and economic activities.

Q6 (Ecosystem Disturbance):

• Give 4 activities that disturb the balance of ecosystem:
  • Deforestation: Leads to habitat loss, soil erosion, and changes in local climate.
  • Pollution: Contaminates air, water, and soil, harming organisms and disrupting natural processes.
  • Overexploitation of resources: Such as overfishing or overhunting, which can deplete populations and disrupt food webs.
  • Introduction of invasive species: Can outcompete native species, disrupt food chains, and alter habitats.

Q7 (Car Seat Belt):

• Explain how car seat belt operates to protect the driver:
  • In a collision, a seat belt applies a restraining force to the driver, increasing the time over which the driver's body decelerates. This longer deceleration time reduces the impact force exerted on the driver, preventing them from hitting the dashboard or windshield and distributing the force over stronger parts of the body.

Q8 (Solids Uses):

• State 2 uses of solids in your daily life:
  • Construction: Materials like wood, concrete, and steel are used to build houses, furniture, and infrastructure.
  • Tools and utensils: Metals, plastics, and ceramics are used to make everyday tools, cooking utensils, and containers.

Q9 (Useful Liquids):

• Identify 3 useful liquids in our daily lives:
  • Water: Essential for drinking, cooking, cleaning, and hygiene.
  • Cooking oil: Used for frying, baking, and as an ingredient in many foods.
  • Fuel (e.g., petrol/diesel): Powers vehicles and machinery for transportation and various tasks.

Q10 (Colloidal Effect):

• a) Define colloidal effect:
  • The colloidal effect, also known as the Tyndall effect, is the scattering of light by particles in a colloid or suspension, making the path of a light beam visible through the mixture.
• b) State examples of colloid:
  • Milk
  • Fog
  • Smoke

Q11 (Cellular Structures):

• State the functions of the following cellular structures:
  • a) Mitochondrion: The "powerhouse" of the cell, responsible for cellular respiration and producing ATP (energy currency).
  • b) Vacuole: Stores water, nutrients, and waste products; in plant cells, it also maintains turgor pressure.
  • c) Nucleus: Contains the cell's genetic material (DNA) and controls cell growth, metabolism, and reproduction.
  • d) Cell membrane: A selectively permeable barrier that regulates the passage of substances into and out of the cell and provides protection.
  • e) Chloroplast: The site of photosynthesis in plant cells, where light energy is converted into chemical energy (sugars).

Q12 (Acid-Base Indicators):

• a) What are acid-base indicators?
  • Acid-base indicators are substances that change color in response to changes in pH, allowing for the visual determination of whether a solution is acidic, basic, or neutral.
• b) State 3 examples of acid-base indicators:
  • Litmus paper
  • Phenolphthalein
  • Methyl orange

Q13 (Acids Properties):

• State 3 chemical properties of acids:
  • They react with metals to produce hydrogen gas and a salt.
  • They react with bases (or alkalis) in a neutralization reaction to form a salt and water.
  • They react with carbonates to produce carbon dioxide gas, water, and a salt.

Q14 (Lemonade Acidity Test):

• Describe how you would test for the acidity of a lemonade:
  • To test the acidity of lemonade, you can use pH paper or litmus paper. Dip a strip of the paper into the lemonade. If the pH paper shows a value below 7 (typically 2-3 for lemonade) or the blue litmus paper turns red, it indicates that the lemonade is acidic.

Q15 (Green Economy):

• a) What green economy?
  • A green economy is an economy that aims for sustainable development without degrading the environment. It is characterized by low carbon emissions, resource efficiency, and social inclusiveness.
• b) State two primary objectives of green economy:
  • To reduce environmental risks and ecological scarcities.
  • To promote sustainable development and social equity, creating green jobs and fostering economic growth.

Q16 (Ohm's Law Calculation):

• A voltage of 5V is applied across a 100 resistor. Calculate the amount of current flowing through it.