4th feb test

• What are the three states of matter?

  Solids, liquids, and gases
• Why are solids and liquids considered incompressible?

  There are no gaps between their particles
• How do the particles in solids differ from those in liquids?

  Solids have fixed size and shape
• What allows liquids to change shape?

  Particles are free to move
• What makes gases compressible?

  Large gaps between the particles
• What is the formula for density?

  Density = mass / volume
• What does the density of a material represent?

  Its mass per unit volume
• What is the method to investigate the density of solids and liquids?

  1. Set up equipment.
  2. Record initial water height and mass.
  3. Add solid/liquid to measuring cylinder.
  4. Record new water height.
  5. Calculate volume by subtracting heights.
  6. Calculate density using density formula.
• What is the independent variable in the density investigation?

  The material being tested
• What are the dependent variables in the density investigation?

  Volume and mass
• Why must the temperature be controlled during the density investigation?

  To ensure accurate volume measurements
• What happens if a solid less dense than water is tested?

  Volume measurement will be inaccurate
• What must be used when reading the measuring cylinder?

  The bottom of the meniscus
• What is a change of state?

  A physical change of matter
• What happens to particles as temperature increases?

  They gain energy
• What occurs at the melting point of a substance?

  Particles overcome intermolecular forces
• Why does temperature remain constant during a change of state?

  Energy is used to change the state
• What is latent heat of fusion?

  Energy to change solid to liquid
• What is latent heat of vaporisation?

  Energy to change liquid to gas
• How do intermolecular forces vary among states of matter?

  Strongest in solids, weakest in gases
• What is the word equation for photosynthesis?

  Carbon dioxide + water → glucose + oxygen
• Why is photosynthesis considered an endothermic reaction?

  It takes in energy from sunlight
• What is the role of chlorophyll in photosynthesis?

  It traps energy from sunlight
• What is a limiting factor in photosynthesis?

  The factor that restricts the reaction rate
• How does temperature affect the rate of photosynthesis?

  Higher temperature increases the rate
• What happens to the rate of photosynthesis at 45°C?

  It drops to zero
• How does carbon dioxide concentration affect photosynthesis?

  Higher concentration increases the rate
• What happens when CO₂ concentration reaches a certain point?

  It no longer limits the reaction rate
• How does light intensity affect the rate of photosynthesis?

  Higher intensity increases the rate
• What happens when light intensity reaches a certain point?

  It no longer limits the reaction rate
• How does chlorophyll concentration affect photosynthesis?

  It may change with mineral availability
• What are the products of photosynthesis used for in plants?

  • Glucose for respiration
  • Building materials for growth
  • Stored energy for later use
• Why do substances with giant covalent structures have high melting points?

  Strong covalent bonds require large energy to break
• What defines a chemical change?

  It turns a substance into something new
• What are the properties of substances with giant covalent structures?

  High melting points and cannot conduct electricity
• What is the particle model of matter?

  • Describes arrangement of particles in states
  • Explains properties of solids, liquids, gases
  • Helps understand changes of state and behavior