sblock Elements 2 Question 16
17. $\mathrm{MgSO} _{4}$ on reaction with $\mathrm{NH} _{4} \mathrm{OH}$ and $\mathrm{Na} _{2} \mathrm{HPO} _{4}$ forms a white crystalline precipitate. What is its formula? $(2006,3 \mathrm{M})$
(a) $\mathrm{Mg}\left(\mathrm{NH} _{4}\right) \mathrm{PO} _{4}$
(c) $\mathrm{MgCl} _{2} \cdot \mathrm{MgSO} _{4}$
(b) $\mathrm{Mg} _{3}\left(\mathrm{PO} _{4}\right) _{3}$
(d) $\mathrm{MgSO} _{4}$
(1993, 1M)
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Answer:
Correct Answer: 17. (a)
Solution:
- Magnesium ammonium phosphate is precipitated out.
$\mathrm{MgSO} _{4}+\mathrm{NH} _{4} \mathrm{OH}+\mathrm{Na} _{2} \mathrm{HPO} _{4} \longrightarrow \mathrm{Mg}\left(\mathrm{NH} _{4}\right) \mathrm{PO} _{4} \downarrow+\mathrm{Na} _{2} \mathrm{SO} _{4}$
