exam q

• What does the plum pudding model represent?

  The atom as a whole
• What is the negative particle in the plum pudding model?

  Electron
• Why is the total positive charge in every atom of an element always the same?

  Because every atom of an element has the same number of protons
• What experiment led to the nuclear model of the atom?

  The alpha particle scattering experiment
• What was the speed of the alpha particles in the experiment?

  Seven percent of the speed of light
• How do you determine seven percent of the speed of light?

  By dividing the speed of light by 100 and multiplying by 7
• What is the radius of a hydrogen atom?

  $2.5 \times 10^{-11} \text{ meters}$
• What is the method to find the density of an irregular shaped object?

  Density is mass divided by volume
• How do you measure the mass of the object in the density experiment?

  Using a mass stop pan balance
• How do you measure the volume of the irregular object?

  Using a displacement canister and a measuring cylinder
• What should you do with the displacement canister before measuring the volume?

  Fill it with water to the level of the spout
• What happens when the object is placed in the displacement canister?

  The displaced water collects in the measuring cylinder
• How do air particles move in a gas canister?

  They move in random directions with varying speeds
• What happens to the movement of air particles when the temperature inside the canister increases?

  The average speed and kinetic energy of the particles increase
• Why could an increase in temperature inside the canister be dangerous?

  Because the pressure increases and the canister could explode
• What happens to the pressure of the air in the canister when air escapes?

  The pressure decreases
• What happens to the volume of air when it is released from the canister?

  The volume increases as the pressure decreases
• What was the Chernobyl disaster?

  A nuclear accident that happened in 1986
• What types of radiation were emitted during the Chernobyl disaster?

  Alpha, beta, and gamma radiation
• What is an alpha particle?

  It has a mass of 4 and a charge of +2
• What is true about beta radiation?

  It has no mass and a charge of -1
• What is true about gamma radiation?

  It has zero charge and zero mass
• How does cavity wall insulation reduce unwanted energy transfers?

  • Thick layer of insulation
  • Low thermal conductivity
  • Reduces energy transfer by conduction
• What equation is used to calculate the power of the boiler?

  Power = Energy transfer / Time
• What does Kirchhoff's law state about current at a junction?

  The current into a junction equals the current out of the junction
• How do you calculate the charge that flows through the cell in one minute?

  Charge = Current × Time
• What is the unit of charge?

  Coulombs
• How does the resistance of an LDR change with light intensity?

  Resistance decreases as light intensity increases
• What happens to the voltmeter reading across the LDR when light intensity increases?

  The voltmeter reading decreases
• What happens to the ammeter reading when the light intensity increases?

  The ammeter reading increases
• What are the changes in energy stores when a gas boiler heats water?

  • Chemical energy in fuel decreases
  • Thermal energy in water increases
  • Thermal energy in air increases
• How do environmental conditions affect the readings on the voltmeter and ammeter in the circuit?

  Changes in light intensity affect the resistance of the LDR, altering the readings
• What happens to the total resistance of the circuit when the light intensity increases?

  The total resistance decreases
• What type of paper is the GCSE Combined Science Trilogy Paper discussed in the material?

  Chemistry Paper One
• What is the focus of the first question in the paper?

  Electrolysis of a copper chloride solution
• What gas is produced at the positive electrode during the electrolysis of copper chloride solution?

  Chlorine
• What does the production of copper at the negative electrode indicate about its reactivity?

  Copper is less reactive than hydrogen
• Which metals are considered medium reactive in the reactivity series?

  Iron, zinc, and lead
• What is the rule for predicting whether a metal will be produced during electrolysis?

  Compare the metal's reactivity to hydrogen in the reactivity series
• How can you determine the mean mass of copper produced after three minutes based on the given data?

  Add 0.6 to 1.2 to predict the mean mass