Question

A compound `(A)` on heating in Busen flame imparts brick red colouration. `(A)` on heating gives `CO_(2)` gas and a residue `(B)`. The residue `(B)` when treated with water gives `(c )`. On passing an excess of `CO_(2)` through `(C )` in water, a clear solution `(D)` is obtained. On boiling `(D)`, compound `(A)` is reformed.
Compound `(C )` is
A. `Ca(OH)_(2)`
B. `Sr(OH)_(2)`
C. `Ba(OH)_(2)`
D. `[Sr(H_(2)O)_(6)]^(2+)`

Answer 1

Correct Answer - A
Compound `(A)` imparts brick red colouration to the Bunsen flame, hence element present in it is `Ca`.
On heating `(A),CO_(2)` is evolved, hence `(A)` is `CaCO_(3)`.
`underset((A))(CaCO_(3))overset(Delta)rarrunderset("Residue")underset((B))(CaO)+CO_(2)uarr.("Residue"(B)is CaO)`
`underset((B))(CaO)+H_(2)Orarrunderset((C))(Ca(OH)_(2)) [(C) is Ca(OH)_(2)]`
`Ca(OH)_(2) +H_(2)O +underset("Excess")(CO_(2)) rarr underset((D))(Ca(HCO_(3))_(2)`
`underset((D))(Ca(HCO_(3))_(2) overset(Delta)rarr underset((A))(CaCO_(3) +H_(2)O +CO_(2)`