Question

There are four sketches below. The first sketch shows a sample of Substance X. The three sketches underneath it show three different changes to the sample. You must decide whether each of these changes is possible. If a change is possible, you must also decide whether it is a physical change or a chemical change. Each sketch is drawn as if the sample were under a microscope so powerful that individual atoms could be seen. Also, you should assume that you can see the entire sample, and that the sample is in a sealed box, so that no matter can enter or leave. Sample of Substance X Change 1 Change 2 Change 3 Change 1 is: impossible O a physical change O a chemical change Change 2 is: impossible a physical change a chemical change Change 3 is: impossible a physical change a chemical change x 6 ?

Answer 1

The atoms mass remains same in chemical change. The reactant has only one kind of atoms. Each molecule contains two red atoms. The total number of atoms in the starting figure are 24. First change: The composition of the molecule are changed, new atoms are present. A chemical change cannot form new atoms. This is an impossible change.

Second change: The composition is again changed. Law of conservation of mass is followed. The total number of atoms are 24, as in the starting molecule. This is a possible chemical change. Third change: The arrangement of molecules is changed. The total atoms are 24, which is same as the starting molecule. This is a physical change.