An unknown metal X when placed in copper sulphate solution, red brown pieces of copper fall to the bottom of the test tube. When metal X is placed in aluminium sulphate solution, no change is observed. Metal X can be
A Sodium
B Potassium
C Iron
D Calcium.
it will be calcium as ,iron is below aluminium in the reactivity series and the metal 'X' is more reactive than Al. as K