`NaPO_(3)` can significantly react with how many of the following ?
`CaCl_(2), MgSO_(4), CaO, Na_(2)CO_(3), " dry " HCl, (HCO_(3))_(2), Na_(3)PO_(4)`

Answer

6

Explanation

`CaCl_(2) + NaPO_(3) rarr` Forms chelate complex with `Ca^(2+), [Ca(P_(3)O_(9))_(2)]^(4-)`, used in softening of hard water.
`MgSO_(4) + NaPO_(3) rarr` Forms chelate complex with `Mg^(2+), [Mg(P_(3)O_(9))_(2)]^(4-)`, used in softening of hard water
`CaO + NaPO_(3) rarr NaCaPO_(4)`
`Na_(2)CO_(3) + NaPO_(3) rarr Na_(3) PO_(4) + CO_(2)`
dry `HCl + NaPO_(3) rarr` No reaction
`Ca(HCO_(3))_(2) + NaPO_(3) rarr` Forms chelate with `Ca^(2+), [Ca(P_(3)O_(9))_(2]^(4-)` used in softening of hard water.
`Na_(3)PO_(4) + NaPO_(3) rarr Na_(4)P_(4)O_(7)`