Ionic bonds hold NaCl together
Ionic bonds are forces that hold together electrostatic forces of attractions between oppositely charged ions. Ionic bonds have an electronegativity difference greater than or equal to 2. Covalent bonds have an electronegativity difference that is less than 2.
Color, the other answers arent changing the substance into something different
1. base
2. neutral
3. acid
4. base
If this is what you meant, hope it helps