Question

Of the three metals X, Y and Z. 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.

Answer 1

X reacts with cold water. Hence , the element should be Calcium

 Ca + H₂O → Ca(OH)₂ + H₂ 

Y reacts with hotwater, Hence, it is "Magnesium" 

Mg + H₂O → Mg(OH)₂ + H₂ 

Z reacts with steam only. Hence , it is Iron

 Fe + H₂O → Fe₂O₃+ H₂

Arranging in ascending order (increasing order of reactivity) 

Fe < Mg < Ca