The answer to the question is Option C. But can someone explain why it is the answer? The question is in the link. It is question 7 of multiple choice.
http://educationstandards.nsw.edu.au/wps/wcm/connect/2faef657-b3bb-4934-a797-b55f5b655c7a/chemistry-hsc-exam-2013.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-2faef657-b3bb-4934-a797-b55f5b655c7a-lG9AkG9
http://educationstandards.nsw.edu.au/wps/wcm/connect/2faef657-b3bb-4934-a797-b55f5b655c7a/chemistry-hsc-exam-2013.pdf?MOD=AJPERES&CACHEID=ROOTWORKSPACE-2faef657-b3bb-4934-a797-b55f5b655c7a-lG9AkG9