9701 MCQ Solution 6

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Question 6: [Physical > Bonding]:

Which is the most likely shape of a molecule of hydrazine, N₂H₄?

Reference: Past Exam Paper – November 2002 Paper 1 Q6

Solution 6:

Answer: D.

The nitrogen atoms in hydrazine have 3 bonds. Each nitrogen atom has 5 electrons in its outer shell. If 3 of these electrons are used to form bonds, 1 with the other nitrogen atom, 1 with 1 hydrogen atom, 1 with another hydrogen atom, it will leave 2 electrons in the nitrogen atom’s outer shell. These 2 electrons will form a lone pair of electrons. Thus surround either nitrogen atom are 3 bonded pair of electrons and 1 lone pair of electrons. Thus the bond angle in either of the nitrogen atoms must 107, due to the repulsion that this combination of lone and bonded pairs of electrons causes.