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

Explanation

Given that X reacts with cold water, Y reacts with hot water and Z reacts steam only. Hence, 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 reacts with 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.