Why is ph3 bond angle less than nh3. Numerically, Bond angle of N H 3 = 107 ∘ Bon...

Why is ph3 bond angle less than nh3.  Numerically, Bond angle of N H 3 = 107 ∘ Bon...Why is ph3 bond angle less than nh3.  Numerically, Bond angle of N H 3 = 107 ∘ Bon...