Question

Which bond angle `theta` would result in the maximum dipole moment for the triatomic `YXY`?
A. `theta=90^(@)`
B. `theta=120^(@)`
C. `theta=150^(@)`
D. `theta=180^(@)`

Answer 1

(a) `mu=sqrt(mu_(1)^(2)+mu_(2)^(2)+2mu_(2)mu_(2) cos theta )`
If `theta=90^(@)`, `mu` is maximum.
Because `cos90^(@)`=0, since, the angle increases from 90to 180, the value of `cos theta` becomes more and more negative and hence resultant decreses. Thus, dipole moment is maximum, when `theta=90^(@)`.