The ‘green rust’ of copper is scrapped and dissolved in water. When litmus paper is dipped in it, what will be the change in colour ?
Purple to red
Red to blue
Green to purple
blue to green
Copper oxide is the green rust. It is basic in nature and will turn red litmus paper blue.
Which colour change is observed when dilute HCl is added to a beaker containing copper oxide?
What will be the colour change on adding common salt dissolved in water to red litmus paper as well as blue litmus paper?