Which of the following will not undergo a displacement reaction

To determine which reaction will not undergo a displacement reaction, we need to apply the reactivity series for metals and halogens. A displacement reaction occurs when a more reactive element displaces a less reactive element from its compound.

Let's analyze each option:

• A. Magnesium + sodium fluoride
  • This involves two metals: Magnesium ($\text{Mg}$) and Sodium ($\text{Na}$) in sodium fluoride ($\text{NaF}$).
  • According to the metal reactivity series, Sodium ($\text{Na}$) is more reactive than Magnesium ($\text{Mg}$).
  • A less reactive metal cannot displace a more reactive metal from its salt solution.
  • Therefore, $\text{Mg(s)} + NaF(aq) \rightarrow \text{