Ge has an electronic configuration: [Ar], 3d¹⁰, 4s², 4p²
Pb has an electronic configuration: [Xe], 4f¹⁴, 5d¹⁰, 6s², 6p²
As is evident from the electronic configuration, the inert pair effect is more pronounced in Pb due to poor shielding by the d- and f-electrons, and hence the +4 oxidation state in lead is less stable and Pb (IV) is a powerful oxidising agent.
On the other hand, Ge (II) is a strong reducing agent because it can easily be oxidised to Ge(IV).

SnO₂ is amphoteric in nature.

SnO₂ + 4H⁺ → Sn⁺⁴ + 2H₂O

SnO₂ + 2H₂O + 2OH^- → [Sn(OH)₆]^2-

SiO₂ is amphoteric in nature.

2NaOH + SiO₂ → Na₂SiO₃ + H₂O

4HF + SiO₂ → SiF₄ + 2H₂O

Sugar of lead is lead acetate, i.e. Pb(CH₃COO)₂.
White lead is basic lead carbonate, i.e. 2PbCO₃.Pb(OH)₂.

At 13.2 °C (about 56 °F) or below, pure tin transforms from the silvery, ductile, metallic allotrope white α-tin to brittle, nonmetallic, β-form grey tin with a diamond cubic structure.

Tin was the major metal used to make buttons in the French army's uniforms. When the Napoleon's army took on the Russian's, the severe Russian temperatures approached -30°C, which led to the disintegration of the crystalline form of tin causing fatal maladies in the soldiers.

(B) Carbon does not form dπ-dπ bond because of the absence of d-orbital.
(D) Silicon carbide has three-dimensional structures with each silicon and carbon being tetrahedrally surrounded by four atoms of the different kinds. In each case. carbon is tetrahedrally is surrounded by four silicon atoms and vice versa.

COCl₂ is phosgene which is a toxic gas. Phosphine is PH₃.

Mellitic acid, also called graphitic acid or benzenehexacarboxylic acid, can be formed by reaction of graphite with hot and concentrated HNO₃.
C₃O₂ (carbon suboxide) is a foul-smelling lacrimatory (tear-stimulating) gas produced by the dehydration of malonic acid, CH₂(COOH)₂, with P₄O₁₀.

CO is toxic because it has the ability to form a complex with haemoglobin in blood, and hence can deprive the body of oxygen.

Bauxite, containing high percentage of silica, can be purified by Serpeck's process. In this process, finely powdered bauxite is mixed with coke and the mixture is heated to 1800°C in a current of nitrogen. The AlN thus obtained is reacted with hot and dilute NaOH, produced NaAlO₂ and excess AlN is hydrolysed and Al(OH)₃ is formed.

Al₂O₃ + 3C + N₂ → 3AlN + 3CO

SiO₂ + 2C → Si­ + 2CO

AlN + NaOH → NaAlO₂ + NH₃

NaAlO₂ + 2H₂O → Al(OH)₃ + NaOH

AlN + 3H₂O → Al(OH)₃ + NH₃

To prepare a silicon polymer containing 'n' Si-O-Si linkages, the total number of chain-building units, R₂Si(OH)₂ required is (n - 1). Thus, the number of R₂Si(OH)₂ units needed is 9.