TG EAMCET 4 May 2025 Shift 1 Paper

Step 1: Reaction with Lithium Aluminium Hydride
When boron trifluoride (BF3) reacts with lithium aluminium hydride (LiAlH4) in ether, it forms lithium fluoride (LiF), aluminium fluoride (AlF3), and diborane (B2H6) :
4BF3+3LiAlH4

‌ Ether ‌

‌───────▶‌

3LiF+3AlF3+B2H6
Step 2: Naming the Product X
So, here X=B2H6 (which is called diborane).
Step 3: Reaction of X with Ammonia
Diborane (B2H6) reacts with ammonia (NH3) to first form an adduct, which is a combined compound: [B2H6⋅2NH3].
Step 4: Heating to Get Z
When this adduct is heated, it breaks down to give borazine (B3N3H6), which is compound Z, and hydrogen gas (H2) :
2B2H6+2NH3→[B2H6⋅2NH3]→2B3N3H6(Z)+H2
Step 5: Counting Sigma (σ) and Pi(π) Bonds in Z
Borazine ( B3N3H6 ) is a ring, and its bonds are:
There are 6 sigma ( σ ) bonds between B and N in the ring.
There are 3 sigma ( σ ) bonds between B and H .
There are 3 sigma (σ) bonds between N and H .
So, the total number of σ bonds (x) is: 6+3+3=12.
There are 3 pi ( π ) bonds ( y ) in the ring.
So, x+y=12+3=15.