Question

Aluminium carbide on reaction with heavy water gives a carbon compound X. The hybridization in X is

• A. sp
• B. $\text{sp}^2$
• C. $\text{sp}^3$
• D. $\text{dsp}^2$

Hint:

$\text{Al}_4\text{C}_3$ and $\text{Be}_2\text{C}$ are methanides because they produce methane ($\text{CH}_4$) on hydrolysis.
Since deuterium is an isotope of hydrogen, the hybridization of $\text{CD}_4$ remains identical to that of $\text{CH}_4$ ($\text{sp}^3$).

Answer 1

The Correct Option is C

Step 1: Write the reaction with heavy water.
Aluminium carbide is an ionic carbide built from $\text{C}^{4-}$ ions, and reacting it with $\text{D}_2\text{O}$ instead of ordinary water simply replaces H with D: \[ \text{Al}_4\text{C}_3 + 12\,\text{D}_2\text{O} \rightarrow 4\,\text{Al(OD)}_3 + 3\,\text{CD}_4 \]
Step 2: Identify compound X.
X is $\text{CD}_4$, the deuterated analogue of methane, where carbon is bonded to four deuterium atoms.
Step 3: Work out the hybridisation from the steric number.
Carbon here forms four sigma bonds and holds no lone pairs, giving a steric number of 4, which always corresponds to sp3 hybridisation with tetrahedral geometry.
Final answer: Option 3, X is $\text{CD}_4$ with sp3 hybridised carbon.