# Group V cations are precipitated in form of carbonates $\left ( NH_{4} \right )_{2}.CO_{3}$  why can we not use $Na_{2} CO_{3}$ instead of $\left ( NH_{4} \right )_{2}CO_{3}$ Option 1) Because $Na_{2}CO_{3}$ will precipitate $MgCO_{3}$ Option 2) Because $Na_{2}CO_{3}$ in insoluble in water Option 3) Because it is an ionic compound Option 4) None of these

As we discussed in concept

Test of Carbonate ion -

Add $BaCl_2$  Solution which give white precipitate

$Ba^{2+} + CO^{2-}_3 \rightarrow BaCO_3 \: (white)$

- wherein

White ppt confirm the $CO^{2-}_3 ions$

$Na_{2}CO_{3}$ is highly ionised electrolyte, producing very high concentration of carbonic ions. Thus, precipitating $MgCO_{3}$

Option 1)

Because $Na_{2}CO_{3}$ will precipitate $MgCO_{3}$

This option is correct.

Option 2)

Because $Na_{2}CO_{3}$ in insoluble in water

This option is incorrect.

Option 3)

Because it is an ionic compound

This option is incorrect.

Option 4)

None of these

This option is incorrect.

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