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Questions and Answers
Papers 1 and 2 contain questions across three cognitive levels.
False
The total marks for Paper 2 in Chemistry is 150.
True
The weight of remembering in Paper 1 is 5%.
False
The duration for completing both papers is the same, which is 3 hours.
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In Physics, the weight for applying and analyzing questions is 40%.
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The Mechanics section in Paper 1 accounts for 75 marks.
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The skills in Physical Sciences include forming an investigative question.
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In Paper 2, the matter and materials section has a weight of 58 marks.
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Mass is defined as the product of an object's weight and its acceleration due to gravity.
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Momentum is a vector quantity that has the same direction as the velocity of the object.
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Newton's second law in terms of momentum states that force is equal to the mass times the speed of an object.
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Impulse is calculated using the time for which a net force acts on an object multiplied by the change in momentum.
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An example of a situation that increases momentum is when a soccer ball is kicked in the direction it is already moving.
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Weightlessness occurs when the gravitational force acting on an object is infinitely large.
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The momentum of an object can be defined as the sum of all forces acting on it.
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Inelastic collisions conserve momentum and kinetic energy.
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An atomic absorption spectrum is created when an atom transitions from a lower energy state to a higher energy state.
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When light passes through a cold gas, it produces a continuous spectrum with dark lines.
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An atomic emission spectrum contains only dark lines and is continuous in nature.
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1 mole of any gas occupies 22.4 dm3 at standard temperature and pressure.
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The conservation of mass implies that the total mass of reactants equals the total mass of products in a balanced chemical equation.
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Under identical conditions of temperature and pressure, different gases occupy different volumes even if their moles are equal.
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In stoichiometric calculations, the empirical formula represents the actual number of atoms in a molecule.
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The percentage yield of a chemical reaction can be calculated through stoichiometric methods.
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Endothermic reactions are characterized by ΔH > 0.
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Exothermic reactions require energy input to proceed.
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Activation energy is the maximum energy required for a reaction to occur.
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The reaction rate is defined as the change in concentration of reactants or products over time.
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A catalyst increases the activation energy of a reaction.
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In a potential energy versus course of reaction graph, an endothermic reaction will have a downward slope.
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The collision theory states that a reaction occurs when particles collide with sufficient energy.
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The nature of reactants does not influence the rate of chemical reactions.
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As the concentration of reactant ions increases, the potential difference of a galvanic cell (Vcell) increases.
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The direction of electron flow in a galvanic cell is from the oxidizing agent to the reducing agent.
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The salt bridge in a galvanic cell serves to complete the circuit by allowing the movement of ions between the two half-cells.
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A half-cell that undergoes oxidation will have a higher standard reduction potential than one that undergoes reduction.
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Cell notation for an inert electrode includes the species involved along with the inert material.
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The overall cell reaction in a galvanic cell is obtained by combining the oxidation and reduction half-reactions.
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The emf of a standard galvanic cell will be negative if the reaction is spontaneous under standard conditions.
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Galvanic cells achieve equilibrium when the Vcell is equal to 0.
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Study Notes
Examination Guidelines
- Papers 1 and 2 include questions across four cognitive levels:
- Remembering (Recall) - 15%
- Understanding (Comprehension) - 35% to 40%
- Applying and Analysing - 40% to 35%
- Evaluating and Creating (Synthesis) - 10%
Paper 1: Physics Focus
- Total marks for Paper 1: 150
- Duration: 3 hours
- Content:
- Mechanics - 65 marks
- Waves, Sound and Light - 15 marks
- Electricity and Magnetism - 55 marks
- Matter and Materials - 15 marks
Paper 2: Chemistry Focus
- Total marks for Paper 2: 150
- Duration: 3 hours
- Content:
- Chemical Change - 92 marks
- Matter and Materials - 58 marks
Skills in Physical Sciences
- Identify and Question Phenomena: Formulate an investigative question that probes the relationship between mass and weight; Explain the concept of weightlessness
Momentum and Impulse
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Momentum:
- Defined as the product of mass and velocity.
- Linear momentum is a vector quantity and has the same direction as the velocity.
- Momentum can be calculated using the formula: p = mv.
- Can be illustrated using vector diagrams, showing the relationship between initial, final, and change in momentum.
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Newton's Second Law of Motion in terms of Momentum:
- The net force acting on an object equals the rate of change of the object's momentum in the direction of the force.
- Expressed in symbols: Fnet = Δp/Δt
- The relationship between net force and change in momentum can be explained in various situations involving changes in velocity, like increasing, decreasing, or reversing directions.
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Impulse:
- Defined as the product of the net force acting on an object and the time the net force acts.
- The Impulse-momentum theorem (FnetΔt = mΔv) can be used to calculate:
- Resultant force
- Time the force is applied
- Change in momentum
- Impulse explains safety considerations in everyday life, such as airbags, seatbelts, and arrestor beds.
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Conservation of Momentum:
- A system in physics implies a collection of objects that interact with each other.
- In a closed system, the total momentum remains constant.
- This conservation principle applies during collisions (elastic or inelastic).
Emission and Absorption Spectra
- Atomic spectra originate from energy transitions within atoms.
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Atomic Absorption Spectrum:
- Occurs when electromagnetic radiation passing through a substance is absorbed.
- For example, when light passes through a cold gas, atoms absorb characteristic frequencies and dark lines appear on a continuous spectrum.
- The frequencies of absorption lines are unique to the specific atom in the gas.
-
Atomic Emission Spectrum:
- Formed due to an atom transitioning from a higher to a lower energy state, emitting electromagnetic radiation.
- For example, atoms in a hot gas emit light at characteristic frequencies, creating a line spectrum with colored lines specific to the emitting atoms.
- The frequencies of emission lines are unique to the type of atom emitting them.
Paper 2: Chemistry
Representing Chemical Change
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Balanced Chemical Equations:
- Represent chemical reactions using chemical formulas, symbols, and coefficients.
- Equations should be balanced to ensure the conservation of atoms and mass.
- Interpreting balanced equations involves understanding the conservation of atoms and mass.
Quantitative Aspects of Chemical Change
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Molar Volume of Gases:
- One mole of any gas occupies 22.4 dm3 at 0 °C (273 K) and 1 atmosphere (101.3 kPa).
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Volume Relationships in Gaseous Reactions:
- Balanced equations can be interpreted in terms of volume relationships for gases under the same temperature and pressure.
- Equal moles of different gases occupy the same volume.
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Concentration of Solutions:
- Calculate the molar concentration of a solution.
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More Complex Stoichiometric Calculations:
- Determine the empirical and molecular formulas of compounds.
- Calculate percentage yield in a chemical reaction: actual yield / theoretical yield * 100%.
Energy and Change
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Energy Changes in Reactions related to Bond Energy Changes:
- Heat of reaction (ΔH): Energy absorbed or released in a chemical reaction.
- Exothermic reactions: Reactions that release energy (ΔH < 0).
- Endothermic reactions: Reactions that absorb energy (ΔH > 0).
- Classify reactions as exothermic or endothermic.
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Activation Energy:
- Minimum energy required for a reaction to occur.
- Activated complex: Unstable transition state between reactants and products.
- Potential energy versus course of reaction graphs can be used to illustrate:
- Catalysed and uncatalysed reactions
- Endothermic and exothermic reactions
Rate and Extent of Reaction
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Rates of Reaction and Factors Affecting Rate:
- Reaction rate: Change in concentration of reactants or products per time unit.
- Calculate reaction rates using the equation: Rate = Δc/Δt (units: mol∙dm-3∙s-1)
- Factors influencing reaction rates:
- Nature of reacting substances
- Surface area
- Concentration (pressure for gases)
- Temperature
- Presence of a catalyst
- Collision theory: Explains reaction rate as a result of particles colliding with sufficient energy to form products.
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Relationship between Current, Potential Difference, Rate, and Equilibrium:
- The potential difference (Vcell) in a galvanic cell is related to the extent the spontaneous cell reaction has reached equilibrium.
- The relationship between Vcell and the concentration of product and reactant ions is qualitative.
- Vcell decreases as the concentration of product ions increases and reactant ions decrease until equilibrium is reached (Vcell = 0, "flat cell").
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Understanding Processes and Redox Reactions in Galvanic Cells:
- Describe the movement of ions in the solutions.
- State the direction of electron flow through the external circuit.
- Write the half-reactions occurring at the electrodes.
- State the function of the salt bridge.
- Use cell notation or diagrams to represent galvanic cells.
- Use standard reduction potentials to calculate the emf of a standard galvanic cell.
- A positive value of the standard emf indicates a spontaneous reaction under standard conditions.
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Description
This quiz covers examination guidelines for Paper 1 and Paper 2 focusing on Physics and Chemistry. It details the cognitive levels assessed, marks distribution, and key content areas, including mechanics and chemical changes. Prepare effectively using this structured overview of the subjects.
