sodium iodide
copper II chloride
sodium sulphate
NaOH
HCl
magnesium nitrate
also is this true: if the metal in the compound is higher in the reactivity series than hydrogen then hydrogen is produced instead of the metal at the positive electrode.
I don't know what your question is, however on the also is this true, yes.
To determine whether the statement is true, we need to consider the reactivity of metals in relation to hydrogen. The reactivity series arranges metals in order of their reactivity, with the most reactive metal at the top and the least reactive at the bottom. If a metal is more reactive than hydrogen, it will displace hydrogen in an aqueous solution.
Let's analyze each compound in your list and determine whether hydrogen or the metal would be produced at the positive electrode:
1. Sodium iodide (NaI) - Sodium (Na) is less reactive than hydrogen, so hydrogen would be produced at the positive electrode.
2. Copper II chloride (CuCl2) - Copper (Cu) is less reactive than hydrogen, so hydrogen would be produced at the positive electrode.
3. Sodium sulfate (Na2SO4) - Sodium (Na) and sulfur (S) are less reactive than hydrogen, so hydrogen would be produced at the positive electrode.
4. Sodium hydroxide (NaOH) - Sodium (Na) is less reactive than hydrogen, so hydrogen would be produced at the positive electrode.
5. Hydrochloric acid (HCl) - Since hydrogen chloride (HCl) is an aqueous solution of hydrogen ions, it does not require a positive electrode for hydrogen to be produced.
6. Magnesium nitrate (Mg(NO3)2) - Magnesium (Mg) is more reactive than hydrogen, so instead of hydrogen, magnesium would be produced at the positive electrode.
Based on these explanations, we can conclude that the statement is generally true, with the exception of compounds like hydrochloric acid (HCl) where hydrogen is already in its ionized form.