Question

(a) Although B—F bond in BF3 is polar but the dipole moment of BF3 is
zero, why?
(b) Write down the Fajans’ rules which increase covalent character of an
ionic bond.
(c) Draw the molecular orbital diagram of He 2 molecule. Calculate its
bond order. Is it stable?

Answer 1

Answer:

For a)

Explanation:

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Answer 2

Answer

(a) The resultant of any two bond moments cancels the third bond moment. Hence the net dipole moment is Zero.

(b) (i) smaller the cation, higher the covalent character.

(ii) higher the charge,higher will be covalent character.

(iii) Larger the anion, higher the covalent character.

(iv) A d-block cation would have more covalent character than a p-block cation.

(c) Refer Attachment.

Helium is unstable.