Sum of the three ionization enthalpies of both the elements are very high. Thus they have no tendency to lose electrons to form ionic compound. Instead they form covalent compounds.

(i) Ge, Sn and Pb show divalency due to inert pair effect, Pb²⁺ is more stable than Pb⁴⁺.
(ii) Due to poor shielding effect of d-electrons in Ga, effective nuclear charge increases as compared to AI. Thus the I.E of Ga is higher than Al.

Fullerenes are the allotropes of carbon. Its structure is like a soccer ball.
They are prepared by heating graphite in electric arc in presence of inert gases such as helium or argon.

(a) R₂SiO
(b) Linear silicons are obtained by the hydrolysis of R₂SiCl₂ (chlorosilanes).

Similarities:
(i) Both have same number of valence electrons.
(ii) Both have similar electronic configuration.
Dissimilarities:
(i) B is a non-metal where Al is a metal.
(ii) B forms acidic oxide whereas Al forms amphoteric oxides.

Hydrolysis of alkyltrichlorosilanes gives cross-linked silicons.

Carbon monoxide
Industrial: 2C(s) + O₂(g) \(\xrightarrow[air]{Limited}\) 2CO(g)
Laboratory: HCOOH \(\xrightarrow[]{H_2SO_4}\) CO + H₂O
                      Formic acid
Carbon dioxide
Industrial: C(s) + O₂(g)\(\xrightarrow[air]{Excess}\)CO₂ (g)
Laboratory: CaCO₃(s) + 2HCl(aq)\(\rightarrow\)CaCl₂(aq) + CO₂(g) + H₂O(l)

Boric acid contains planar BO₃^3- ions which are linked together through hydrogen bonding

Electron deficient species 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 has 8 electrons but it can expand its covalency beyond 4 due to the presence of d-orbitals.
Thus, SiCl₄ should also be considered as electron deficient species.

Solid CO₂, produce cooling and sublimes directly into vapour state. That's why it is used in refrigeration.

CO forms carboxy-haemoglobin complex with haemoglobin (the red pigment which carries oxygen) of blood which is about 300 times more stable than oxygen-haemoglobin complex and thus, it stops the supply of oxygen and hence, leads to death of the person.

Aluminium form [AlF₆]^3- ion because of the presence of vacant d-orbitals due to which it can expand its coordination number from 4 to 6. In this complex Al undergoes sp³d² hybridisation. On the other hand, boron does not form [BF₆]^3- ion, because of the unavailability of d-orbitals as it cannot expand its coordination number beyond four. Hence, it can form [BF₄]^- ion (boron in )  [BF₄]^- ion is sp³ hybridised).

On strong heating, the salt X swells up to to a glassy material Y. It indicates that the salt X is borax.