An aqueous solution of will produce a neutral solution. An aqueous solution of will produce a neutral solution. NaNO2 Li2CO3 NaF NaClO4 NH4ClO4

An aqueous solution of  NaF will produce a neutral solution.

Explanation:

In order to classify the solutions, we need to dissociate all the salts and determine the conjugate pairs of base and acids.

NaNO₂ → Na⁺  + NO₂⁻

Na⁺ comes from the NaOH, a strong base, so the Na⁺ is the conjugate weak acid from the strong base. It will not react. This is a basic salt.

The NO₂⁻  is a conjugate strong base, that comes from the weak acid, nitrous acid. This ion can make hydrolisis.

NO₂⁻  +  H₂O  ⇄    HNO₂   +  OH⁻          Kb

We give OH⁻ to medium, so solution is basic.

Li₂CO₃  →  2Li⁺  +  CO₃⁻²

Li⁺ comes from the LiOH, a strong base, so the cathion is the conjugate weak acid from the strong base. It will not react

The CO₃⁻²  is a conjugate strong base, that comes from the weak acid, carbonic acid. This ion can make hydrolisis.

CO₃⁻²  +  H₂O  ⇄    HCO₃⁻  +  OH⁻      Kb

NaClO₄ →  Na⁺  +  ClO₄⁻

Na⁺ comes from the NaOH, a strong base, so the cathion is the conjugate weak acid from the strong base. It will not react

The ClO₄⁻  is a conjugate strong base, that comes from the weak acid, perchloric acid. This ion can make hydrolisis. This is a basic salt.

ClO₄⁻  +  H₂O  ⇄    HClO₄⁻  +  OH⁻      Kb

NH₄ClO₄  →  NH₄⁺  +  ClO₄⁻

Both ions can make hydrolisis. Ammonium comes from a weak base, so it is the strong conjugate base, and  ClO₄⁻  is a conjugate strong base, that comes from the weak acid, perchloric acid

NH₄⁺  +  H₂O  ⇄  NH₃  +  H₃O⁺         Ka

ClO₄⁻  +  H₂O  ⇄    HClO₄⁻  +  OH⁻      Kb

This sort of salt are generally acid.

NaF  →  Na⁺  + F⁻

As we have seen, Na⁺ comes from the NaOH (a strong base) so it will not react.

This equilibrium can not occur: Na⁺  + H₂O ←  NaOH   +  H⁺

F⁻  comes from a strong acid, HF so it will not also react. This reaction can not occur too: F⁻  + H₂O ←  HF   +  OH⁻

We do not have reaction in this neutral salt, so the pH is neutral.