most needed study

• Always soluble


  $Na^+$$, K^+$$, NH4^+$$, NO3^-$
• Soluble (Sodium)


  $Na^+$
• Soluble (Potassium)


  $K^+$
• Soluble (Ammonium)


  $NH4^+$
• Soluble (Nitrate)


  $NO3^-$