Nitrogen, being smaller in size, can successfully form pπ–pπbonds with different elements having a small size and high electronegativity. For example- nitrogen can easily form pπ–pπ bonds with oxygen, carbon and fluorine.

The melting point of carbon is extremely high. All the elements of group 14 possess diamond-type lattice structure which is highly stable in nature. The process of melting results in the breakage of these highly stable lattice structures. Hence, a large energy is required for the breakage. Down the group, size increases and bond energy of M-M decreases which leads to the decrease in the melting point. Hence, the correct order of increasing melting point is Pb < Ge < Si < C.

Due to non-availability of vacant d-orbitals, carbon cannot exceeds its coordination number to more than four. Thus, CCl4 cannot undergoes hydrolysis.

The oxidation state of fluorine in its compound is always –1 while other elements exhibit a large number of oxidation states (–1, +1, +3, +5, +6, +7). This is because fluorine has the highest electronegativity, so it can never exhibit positive oxidation state.

Both the statements are true but they have no relation with each other. Boron forms only covalent compounds due to its exceptionally small size while all other members of group 13 form both ionic and covalent compounds.

Fluorine is the most reactive among halogens due to its highest electronegativity. It has not the lowest bond enthalpy. Iodine has the lowest bond enthalpy.

N₂O₃ exists as 

Bismuth is an element that forms  bismuth oxychloride which is sold under the name ‘Pearl White’.

Carbides of Be are covalent whereas carbides of other members are ionic. This is because beryllium has the smallest size due to which it forms covalent carbides.

Fluorine is the strongest oxidizing agent due to its highest electronegativity and electron affinity.