7ALP - Understanding Chemical Reactions and Properties (level 10

What is the primary factor that determines the melting point of a substance?

• The size of the particles

• The strength of the attraction between particles

• The colour of the substance

• The volume of the substance

Which of the following best describes the Law of Conservation of Mass?

• Mass can be created or destroyed in a chemical reaction

• Mass is conserved and remains constant in a chemical reaction

• Mass is irrelevant in chemical reactions

• Mass increases in exothermic reactions

Which of the following is a property of non-metallic elements?

• High electrical conductivity

• Malleability

• Brittle and poor conductors of heat

• Lustrous appearance

• Decomposition

• Synthesis

• Displacement

• Combustion

Which factor does NOT affect the rate of a chemical reaction?

• Temperature

• Concentration of reactants

• Colour of reactants

• Surface area of solid reactants

What is the significance of periods in the periodic table?

• They indicate the number of valence electrons

• They represent elements with similar properties

• They indicate the number of electron shells

• They show the atomic mass of elements

Which of the following reactions is exothermic?

• Melting of ice

• Combustion of petrol

• Evaporation of water

• Photosynthesis

What is the term for the process where a solid changes directly into a gas?

• Condensation

• Sublimation

• Evaporation

• Freezing

Which of the following elements is most reactive?

• Helium

• Sodium

• Gold

• Iron

What is the effect of a catalyst on a chemical reaction?

• It increases the activation energy

• It decreases the activation energy

• It changes the products of the reaction

• It has no effect on the reaction rate