Question

Bond angle of PH₃ is less than that of PF₃. Why?

Answer 1

ph3 and pf3  are pyramidal in shape with one lone pair on p but the greater bond angle is due to the resonance in pf3 leading to partial double bond

Answer 2

both PH3 and PF3 are pyramidal in shape with one long pair on p.but PF3 is having greater bond angle than PH3 because resonance in PF3 , leading topartial double bond character.as a result repulsions between P-F bonds are large and hence bond angle is large.