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 is sodium or potassium (Na or K)as it reacts with cold water.
`2Na+underset("Cold water")(2H_(2)O)tounderset("hydroxide")underset("Sodium")(2NaOH)+H_(2)`
Y is magnesium (Mg) as it reacts with hot water.
`2Na+underset("Hot water")(2H_(2)O)tounderset("hydroxide")underset("Magnesoium")(Mg(OH)_(2))+H_(2)" "M`
Z is iron (Fe).
`3Fe+underset("Steam")(4H_(2)OtoFe_(3)O_(4)+4H_(2)`
Increasing order of reactivity
`ZltYltXorFeltMgltNa//K`