The pair that does NOT require calcination is :

Options

A. `Fe_(2)O_(3)` and `Ca_(2)CO_(3).MgCO_(3)`
B. `ZnCO_(3)` and `CaO`
C. `ZnO` and `Fe_(2)O_(3).xH_(2)O`
D. `ZnO` and `MgO`

Answer

D

Explanation

`ZnCO_(3) overset(Delta)rarrZnO + CO_(2) " "Fe_(2)O_(3).xH_(2)O overset(Delta)rarrFe_(2)O_(3) + xH_(2)O`
`CaCO_(3) overset(Delta)rarr CaO + CO_(2) " "ZnO overset(Delta)rarr X`
`MgCO_(3) overset(Delta)rarr MgO + CO_(2) " " MgO overset(Delta)rarr X`