Question

of the three matels X,Y and Z,X reacts with cold water, Y with hot water and Z with steam only. Identify X,Y & Z and also arrange them in order of increasing reactivity

Answer 1

We are given that X reacts with cold water, Y reacts with hot water and Z reacts with steam only. Thus X will be a metal that occurs earlier in the reactivity series. It could be potassium, sodium or calcium. Metal Y reacts with hot water, so metal Y is magnesium as magnesium reacts very slowly with cold water but readily reacts with hot water. Metal Z is Zinc, as it is well known that zinc does not react with cold water, extremely slowly with hot water but readily with steam.

Answer 2

X is sodium.
Y is magnesium.
Z is Aluminium.

They can be arranged in a reactivity series as following.
Sodium>magnesium>Aluminium.

Hope this helps you.