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 so, X could be sodium or potassium metal.
  `2"Na" + 2"H"_2"O" overset("Heat")(->) 2"Cu"_2"O" + 2"SO"_2`
• Y reacts with hot water so, Y could be magnesium or calcium.
  `"Ca" + 2"H"_2"O" -> "Ca"("OH")_2 + "H"_2`
• Z reacts with steam only so, Z could be Aluminium, iron or zinc.
  `4"Fe" + 6"H"_2"O" -> 2"Fe"_2"O"_3 + 6"H"
  _2`

Out of the identified metals, X is the most reactive and Z is the least reactive so, in order if increasing reactivity they could be arranged as Z < Y < X.