Question

which of the following metal cannot displace H2 from H2O
Cu . Na . K . Ca . give reason​

Answer 1

copper
In the reactivity series, the metals that come above hydrogen are more reactive than hydrogen and hence they have the ability to displace hydrogen. For example, Sodium(Na), Iron(Fe), Zinc(Zn).
On the other hand, the metals that come below hydrogen in the reactivity series are less reactive than hydrogen and hence they cannot displace hydrogen. For eg, Copper(Cu), Mercury(Hg), Silver(Ag), Gold(Au).
Thus, the correct answer is option (B).