Four equations for enthalpy changes are given below. $\text{Na(g)} \rightarrow \text{Na}^+(g) + e^- \quad \Delta H = W$ $\text{Na(g)} \rightarrow \text{Na}^{2+}(g) + 2e^- \quad \Delta H = X$ $\text{Na(s)} \rightarrow \text{Na(g)} \quad \Delta H = Y$ $\text{Na(s)} \rightarrow \text{Na}^{2+}(g) + 2e^- \quad \Delta H = Z$ Determine the second ionisation energy of sodium.
- A$X$
- B$X - W$
- C$Y - W$
- D$Z - Y$