Let's identify which salt precipitates out of the solution when ions [tex]\( Na^+ \)[/tex], [tex]\( PO4^{3-} \)[/tex], [tex]\( V^{3+} \)[/tex], and [tex]\( Cr \)[/tex] are mixed based on solubility rules.
1. Sodium Ion ([tex]\( Na^+ \)[/tex]): Salts containing sodium ions are generally soluble in water. This includes [tex]\( NaCl \)[/tex] and [tex]\( Na3PO4 \)[/tex].
2. Phosphate Ion ([tex]\( PO4^{3-} \)[/tex]): Phosphates are generally insoluble in water except for those of Group 1 (alkali metals like sodium, potassium) and ammonium. This means that salts such as [tex]\( VPO4 \)[/tex] (Vanadium(III) phosphate) can be insoluble.
3. Vanadium(III) Ion ([tex]\( V^{3+} \)[/tex]): Vanadium(III) salts need specific consideration. While chlorides like [tex]\( VCl3 \)[/tex] are typically soluble, phosphates of other metals generally are not.
4. Chromium ([tex]\( Cr \)[/tex]): Chromium alone in its elemental form will not form any salts directly from this context.
Evaluating the options:
A. [tex]\( VPO4 \)[/tex]: Vanadium(III) phosphate. Given that phosphates are generally insoluble except for those of alkali metals and ammonium, [tex]\( VPO4 \)[/tex] is expected to be insoluble and hence can precipitate out of the solution.
B. [tex]\( Na3PO4 \)[/tex]: Sodium phosphate. This is soluble because sodium salts are generally soluble.
C. [tex]\( VCl3 \)[/tex]: Vanadium(III) chloride. Chlorides are generally soluble except for a few exceptions like AgCl, PbCl2, and Hg2Cl2, making [tex]\( VCl3 \)[/tex] soluble in water.
D. [tex]\( NaCl \)[/tex]: Sodium chloride. This is soluble as sodium salts are generally soluble.
Therefore, the salt that will precipitate out of the solution is:
A. [tex]\( VPO4 \)[/tex]
This results from the fact that of the given ions, the combination of [tex]\( V^{3+} \)[/tex] and [tex]\( PO4^{3-} \)[/tex] will form an insoluble compound.
Final answer:
A. [tex]\( VPO4 \)[/tex]
