Question

8. Why does a colour of copper sulphate solution changes when an iron nail is dipped in it?
9. What happens when dilute HCl is added to iron filings?
10. Why is respiration considered an exothermic reaction?

Answer 1

8 . It is because , when iron is dipped in copper sulphate solution iron displace copper as shown in equation

CUSO4 {COPPER SULPHATE}+FE{IRON NAIL} ---------> FESO4{ IRON SULPHATE} + CU {COPPER}