Question

A sodium salt of an unknown anion when treates with `MgCI_(2)` gives white precipitate only on boling .The anion is
A. `SO_(4)^(2-)`
B. `HCO_(3)^(Θ)`
C. `CO_(3)^(2-)`
D. `NO_(3)^(Θ)`

Answer 1

Correct Answer - b,c
It must be a bicarbonate ion because first magnesium beicarbonate is formed which is soluble , then on heating , magnesium carbonate is formed which is a insoluble and forms a precipitate
`MgCI_(2) + 2NaHCO_(3) rarr underset("soluble")((Mg(HCO_(3))_(2)) + 2NaCI`
`Mg(HCO_(3))_(2) overset(Delta)(to) underset(white)(MgCO_(3) darr) + H_(2)o + co_(2)`