The p-Block Elements

Electron deficient compounds are those in which the central atom in their molecule has the tendency to accept one or more electron pairs. They are also known as Lewis acid. BCl₃ and SiCl₄ both are electron deficient species.
Since, in BCl₃, B atom has only six electrons. Therefore, it is an electron deficient compound.
In SiCl₄ the central atom Si has 8 electrons but it can expand its covalency beyond 4 due to the presence of d-orbitals.

Aluminium reacts with acid as well as base. This shows amphoteric nature of aluminium.
2Al (s) + 6HCl (dil.) →2AlCl₃ (aq) + 3H₂ (g)
2Al (s) + 2NaOH (aq) + 6H₂O (l) →2Na+ [Al (OH)₄]^– (aq) + 3H₂ (g)

In BF₃, boron is sp² hybridized.
? shape of BF₃ = planar.
In [BH₄]^–, boron is sp3 hybridized, thus the shape is tetrahedral.

On heating boric acid above 370 K, it forms metaboric acid, HBO₂ which on further heating yields boric oxide B₂O₃.

H₃B₂O₃ → HBO₂ → B₂O₃

Boric acid is a Lewis acid since it accepts electrons from hydroxyl ion of H₂O molecule. It is not a protic acid.
B (OH)₃ + 2HOH → [B (OH)₄]^– + H₃O⁺

In BCl₃, there is only six electrons in the valence shell of B atom. Thus, the octet is incomplete and it can accept a pair of electrons from water and hence BCl₃ undergoes hydrolysis. Whereas, in CCl₄, C atom has 8 electrons and its octet is complete. That's why it has no tendency to react with water.

In BF₃, central atom has only six electrons after sharing with the electrons of the F
atoms. It is an electron-deficient compound and thus behaves as a Lewis acid.

BCl₃ is quite stable. Because there is absence of d- and f-electrons in boron three valence electrons (2s² 2p_x1) are there for bonding with chlorine atom. In Tl the valence s-electron (6s²) are experiencing maximum inert pair effect. Thus, only 6p¹ electron is available for bonding. Therefore, BCl₃ is stable but TlCl₃ is comparatively unstable.

(i) B to Tl
Common oxidation states are +1 and +3. The stability of +3 oxidation state decreases from B to Tl while +1 oxidation state increases from B to Tl.

(ii) C to Pb
The common oxidation states are +4 and +2. Stability of +4 oxidation state decreases from C to Pb.

Yes, NCERT solutions are enough to prepare for the exam. However, solving the Class 11 Chemistry Chapter 11 textbook solutions are also important to build the conceptual knowledge.