question_answer

\[{{H}_{2}}O\]is dipolar, whereas \[Be{{F}_{2}}\]is not. It is because   [CBSE PMT 1989; 2004]

A)                 \[{{H}_{2}}O\]is linear and \[Be{{F}_{2}}\] is angular       

B)                 \[{{H}_{2}}O\]is angular and \[Be{{F}_{2}}\] is linear

C)                 The electornegativity of F is greater than that of O

D)                 \[{{H}_{2}}O\]involves hydrogen bonding whereas \[Be{{F}_{2}}\]is a discrete molecule

Correct Answer: B

Solution :

           The overall value of the dipole moment of a polar molecule depends on its geometry and shape i.e., vectorial addition of dipole moment of the constituent bonds water has angular structure with bond angle 105° as it has dipole moment. However \[Be{{F}_{2}}\] is a linear molecule since dipole moment summation of all the bonds present in the molecule cancel each other.