The phosphorus trihalides 1PX32 show the following variation in the bond angle X¬P¬X: PF3, 96.3°; PCl3, 100.3°; PBr3, 101.0°; PI3, 102.0°. The trend is generally attributed to the change in the electronegativity of the halogen. (a) Assuming that all electron domains are the same size, what value of the X¬P¬X angle is predicted by the VSEPR model? (b) What is the general trend in the X¬P¬X angle as the halide electronegativity increases? (c) Using the VSEPR model, explain the observed trend in X¬P¬X angle as the electronegativity of X changes. (d) Based on your answer to part (c), predict the structure of PBrCl4