Question

In which of the following $\Delta H_f$ would not be zero?

• A. C(graphite)
• B. $I_2(s)$
• C. $B{r}_2(l)$
• D. red P

Answer 1

Answer: (D)

Red phosphorus has high $\Delta H_f$ because it is less reactive and it is not a stable allotropic form of phosphorus. So its $H_f$ would not be zero.