8. Three ice cubes are floating in water. Mass of the beaker + the ice cubes + the water = 58 g After the ice melts, will the mass of the beaker: a. be greater than 58 g b. be less than 58 g c. stay the same? Explain your choice.
9. State which of the changes listed below are examples of a chemical change and which are examples of a physical change. Explain your answers.
a. Burning diesel in a car engine b. Dissolving sugar in coffee c. A firework exploding d. Cutting paper e. Adding carbon dioxide to drinks f. Using bacteria to make yoghurt from milk
10. If paper is burned, the mass of the paper before burning is greater than the mass of the ashes. Where does the missing mass go?
:Fig. 15.12
Past paper questions
1. Final Examination 2019, Question 4 Natural gas contains methane (CH4
Reactants ). Methane is a fuel.
Methane burns in oxygen to produce carbon dioxide and water. The diagram below represents the reaction.
Products
CH4 :Fig. 15.13
a. Mass is conserved during this reaction. What evidence is there for this? b. The burning of methane is an example of a chemical change. Describe one difference between a physical change and a chemical change.