Which one of the following conversions involve change in both hybridisation and shape?

• A

  $\mathrm{CH}_{4} \longrightarrow \mathrm{C}_{2} \mathrm{H}_{6}$
• B

  $\mathrm{NH}_{3} \longrightarrow \mathrm{NH}_{4}^{+}$
• Correct answer
  C

  $\mathrm{BF}_{3} \longrightarrow \mathrm{BF}_{4}^{-}$
• D

  $\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{H}_{3} \mathrm{O}^{+}$

Solution

(a)

(b)

(c)

(d)

Thus, conversion of $\mathrm{BF}_{3}$ into $\mathrm{BF}_{4}^{-}$involves change in both hybridisation and shape.

Hence, the correct answer is option: 'C'.