This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to all the questions: 1 (ii) Write down four differences between NaCl and C_6H_12O_6. NaCl is an ionic compound, while C_6H_12O_6 (glucose) is a covalent compound*. NaCl has a high melting point (801 °C), while C_6H_12O_6 has a lower melting point* (146 °C). NaCl conducts electricity when molten or dissolved in water, while C_6H_12O_6 does not conduct electricity*. NaCl is an inorganic compound, while C_6H_12O_6 is an organic compound*. 1 (c) (i) State four fundamental units of measurement and their symbols. Length: meter* (m) Mass: kilogram* (kg) Time: second* (s) Electric current: ampere* (A) 1 (c) (ii) What is a derived unit? A derived unit is a unit of measurement that is obtained by multiplying or dividing fundamental (base) units of the International System of Units (SI). Examples include square meter (m^2) for area or meter per second (m/s) for speed. 1 (d) (i) List two examples of worms that infest cattle. Tapeworms* Roundworms* (e.g., Ascaris, hookworms) 1 (d) (ii) State two precautions that could be taken to reduce worm infestation in cattle. Regularly deworming* cattle with appropriate anthelmintics. Practicing rotational grazing* to break the life cycle of worms and reduce pasture contamination. 1 (d) (iii) State four ways in which these worms can harm their host. They compete for nutrients* with the host, leading to malnutrition. They can cause damage to host tissues and organs*, such as the intestines or liver. Some worms cause blood loss*, leading to anemia. They can reduce growth rates* and overall productivity (e.g., milk yield) in cattle. 2 (a) (i) State four ways in which excessive alcohol consumption is harmful to humans. Causes liver damage*, such as fatty liver, alcoholic hepatitis, and cirrhosis. Leads to brain damage* and cognitive impairment. Increases the risk of developing certain cancers*, including those of the mouth, throat, esophagus, and liver. Can result in addiction* and dependence, leading to social and psychological problems. 2 (a) (ii) List two effects of cigarette smoke on humans. Causes lung cancer* and other respiratory diseases like emphysema and chronic bronchitis. Increases the risk of heart disease*, stroke, and other cardiovascular problems. 2 (b) (i) Give the functional groups present in (α) Alcohol: Hydroxyl group* (-OH) (β) Ethylene: Carbon-carbon double bond* (C=C) (γ) Carboxylic acid: Carboxyl group* (-COOH) (δ) Esters: Ester group* (-COO-) 2 (b) (ii) Write down four differences between neutralization and esterification. Reactants*: Neutralization involves an acid and a base, while esterification involves a carboxylic acid and an alcohol. Products*: Neutralization produces a salt and water, while esterification produces an ester and water. Reaction type*: Neutralization is typically an ionic reaction, while esterification is a covalent reaction. Catalyst*: Neutralization usually does not require a catalyst, while esterification typically requires an acid catalyst (e.g., concentrated H_2SO_4). 2 (c) Define the following terms as applied to a simple machine, stating the effect of friction on each of them (i) Mechanical advantage: The ratio of the load (resistance force) to the effort (applied force). Friction reduces* the mechanical advantage of a machine because more effort is needed to overcome friction. (ii) Velocity ratio: The ratio of the distance moved by the effort to the distance moved by the load. Friction does not affect* the velocity ratio, as it is a theoretical value determined by the machine's design. (iii) Efficiency: The ratio of the useful work output to the total work input, often expressed as a percentage. Friction reduces* the efficiency of a machine because some of the input energy is converted into heat due to friction, thus reducing the useful work output. 2 (d) (i) Name two tools used in the preparation of a nursery bed. Spade* Rake* 2 (d) (ii) State four factors you would consider in selecting a site for a nursery. Soil type and fertility*: Needs well-drained, fertile soil. Water availability*: Easy access to a reliable water source for irrigation. Sunlight exposure*: Adequate sunlight for seedling growth. Protection*: Shelter from strong winds, excessive rain, and pests. 2 (d) (iii) Mention two reasons for nursing seeds at the nursery. It allows for better control over environmental conditions* (e.g., watering, pest control) during the critical early stages of plant growth. It helps to protect young seedlings* from harsh weather conditions, pests, and diseases, leading to higher survival rates. 3 (a) (i) State four beneficial effects of microorganisms to humans. Food production*: Used in making bread, cheese, yogurt, and fermented foods. Digestion*: Gut bacteria aid in the digestion of food and synthesis of vitamins. Decomposition*: Break down organic waste and dead organisms, recycling nutrients in the environment. Medicine production*: Used to produce antibiotics and vaccines. 3 (a) (ii) State two reasons why organisms communicate with one another. To attract mates* for reproduction. To warn others of danger* or predators. 3 (b) (i) (α) What is a hydrocarbon? A hydrocarbon is an organic compound that consists entirely of hydrogen and carbon atoms. 3 (b) (i) (β) Name three sources of hydrocarbons? Crude oil* Natural gas* Coal* 3 (b) (ii) Determine how much water should be added to 30cm^3 of 0.2 mol/dm^3 NaCl solution to obtain 0.02 mol/dm^3. Step 1: Identify the given values for initial concentration (C_1), initial volume (V_1), and desired final concentration (C_2). C_1 = 0.2 mol/dm^3 V_1 = 30 cm^3 C_2 = 0.02 mol/dm^3 Step 2: Use the dilution formula C_1V_1 = C_2V_2 to find the final volume (V_2) of the solution. (0.2 mol/dm^3) × (30 cm^3) = (0.02 mol/dm^3) × V_2 Step 3: Solve for V_2. V_2 = 0.2 mol/dm^3 × 30 cm^30.02 mol/dm^3 V_2 = (6)/(0.02) cm^3 V_2 = 300 cm^3 Step 4: Calculate the amount of water that needs to be added by subtracting the initial volume from the final volume. Volume of water added = V_2 - V_1 Volume of water added = 300 cm^3 - 30 cm^3 Volume of water added = 270 cm^3 3 done, 2 left today. You're making progress.