Chemistry

This is a Short Answers Type Questions as classified in NCERT Exemplar

(A) Carbon has small size and large electronegativity, it forms strong n−pπ bonding with two oxygen atoms forming a separate CO₂ molecule.

While in SiO₂ silicon is larger in size with comparatively less electronegativity than carbon it shows no tendency to form n−pπ bonding rather forms Single covalent bond with oxygen. Thus, SiO₂ possess 3D network-like structure in which each Silicon is bonded to 4 oxygen atoms.

(B) Carbon is smaller in size and lacks d-orbitals hence can have a maximum coordination number of four and sp³ hybridisation only.

Whereas Silicon has d-orbital, it can amplify its hybridisation up to sp³d² (CN=6) and can complete its Octet. Therefore, Silicon forms SiF₆²⁻.

whereas the corresponding flugre-compound of carbon is not known.

This is a Short Answers Type Questions as classified in NCERT Exemplar

(A) sarbon in CCl₄ does not have a vacant d-orbital to accommodate the electrons from OH of water molecules. Also CCl₄ is nonpolar covalent compounds whereas H₂O is polar. So, no strong interaction occurs between them. Hence CCl₄ is miscible in water.

Whereas in SiCl₄, silicon has bigger size than carbon and have d-orbitals for accommodation of electrons donated by OH of water in the process of hydroxylation. This leads to a strong interaction and silicon acid Is formed as a product. SiCl₄ is completely miscible in water.

(B) As we move from carbon to silicon, the size increases and electronegativity decreases. This results in the decrease in M-M bond energy. Hence the catenation property decreases.

Bond energy is the amount of energy required to fragment the atoms combined in a molecule are born into separate atoms. Carbon has maximum bond energy as compared to silicon. Therefore, shows maximum catenation property.

This is a Short Answers Type Questions as classified in NCERT Exemplar

The central B atom in BCl₃ has six electrons in its valence shell. As a result, it is an electron-deficient molecule in need of two more electrons to complete its octet. To put it another way, BCl₃ acts as a Lewis acid. NH₃ on the other hand, has a lone pair of electrons that it can easily donate. As a result, NH₃ serves as a Lewis base. As shown below, the Lewis acid (BCl₃) and Lewis base (NH₃) combine to form an adduct:

The valence shell of AlCl₃ contains six electrons. As a result, it is an electron-deficient molecule that requires two additional electrons to complete its octet.

Chlorine, on the other hand, has three lone electron pairs. As a result, to complete its octet, the central Al atom of one molecule accepts a lone pair of electrons from the Cl atom of the other molecule, resulting in the formation of a dimeric structure, as shown below.

This is a Long Answers Type Questions as classified in NCERT Exemplar

2C (s) + O₂ + 4N₂ (g)  2CO (g) + 4N₂ ( g)

Fe₂O₃ (S)+3CO (g) 2Fe (S)+3CO₂

C= tetravalent carbon 

CO= carbon monoxide 

Fe₂O₃= ferric oxide 

CO₂= carbon dioxide 

Tetravalent elements i.e. carbon combines with oxygen to produce carbon monoxide. The reaction occurs at high temperatures and in the presence of nitrogen gas, which acts as a producer gas only. It is not consumed in the reaction. The carbon monoxide formed acts as a reducing agent for ferric oxide, reduces the oxidation state of iron from +3 to zero, and oxidizes itself to form carbon dioxide.