JEE Chemistry 2024 Question with Solution

Given: We need to identify which given molecule/ion has square pyramidal shape.

Find: The correct option.

From the solution, $BrF_5$ has 5 bond pairs and 1 lone pair on the central bromine atom.

Thus, the total number of electron regions is:

So, the electron pair geometry is octahedral.

When one position of an octahedral arrangement is occupied by a lone pair, the molecular shape becomes square pyramidal.

Therefore, $BrF_5$ has square pyramidal shape, so the correct option is C.

Given: The options are $[Ni(CN)_6]^{2-}$, $PCl_5$, $BrF_5$ and $PF_5$.

Find: Which species has square pyramidal shape.

Using the extracted solution content:

1. $BrF_5$ has bromine as the central atom with 5 bonded fluorine atoms and 1 lone pair.
2. Hence its electron pair geometry is octahedral.
3. Its molecular shape is therefore square pyramidal.

Also, the other listed species are not square pyramidal according to the solution discussion:

• $PCl_5$ is trigonal bipyramidal.
• $PF_5$ is trigonal bipyramidal.
• The nickel cyanide complex discussed in the solution is not square pyramidal.

Therefore, the only matching species is $BrF_5$.

So, the correct option is C, i.e. $BrF_5$.

Note: The solution contains a mismatch where it prints option B, but the worked explanation clearly identifies $BrF_5$, which is option C in the provided options.