Properties of covalent compounds - class-XI

Solution:- (C) Covalent bonding involves losing and gaining electrons

Solution:- (B) Shared - low

Compound X consists of molecules, so its covalent compounds and dont have any charged ions to conduct electricity so it will not conduct electricity.

Butane can be written as $CH _3-CH _2-CH _2-CH _3$. The electronegativities of Carbon and hydrogen are almost same and hence none of them is more electronegative than the other. Thus the compound is non polar in nature, as the electrons are equally distributed on the molecule.

According to Fajan's rule, covalent character increases with the charge on the cation. SnCl4 has a +4 charge on the tin ion, which is higher than the +2 charge in SnCl2 or the +1 charge in KCl/CaCl2, leading to greater polarization and more covalent character.

Carbon dioxide $CO _2$ is covalent compound. In this molecule, two non-metals carbon and oxygen share their electrons to form covalent bonding. Remaining all molecules shows formation of ionic bonding.

Like dissolves like. As the compound is volatile and insoluble in water, so compound in non-polar, means it contains covalent bonds.

Covalent compounds have low melting points. are non-conductors of electricity, they exhibit space isomerism because covalent bonds are directional. Covalent compounds reactions are slow because breaking of bond is non-spantaneous.

Polar compound are soluble in polar solvents. As covalent compounds are less polar or non-polar, they are soluble in non-polar solvents like ether and ionic compounds are soluble in polar solvents like water $(H _2O)$.

Covalent solids are soft, have a low melting point (due to relatively weak bonds), and are a poor conductor of electricity (due to absence of free ions).

Graphite is an allotrope (a different structural form) of carbon (so is diamond), but unlike diamond, graphite can conduct electricity. The reason is that graphite consists of flat hexagons, all liked together in a flat plane. The carbons in the hexagons have delocalized pi bonding (pi bonds, along with a sigma bond, make up a double bond) which allows electrons to easily move from atom to atom making it a good conductor of electricity.

Graphite is a mineral made of loosely bonded sheets of carbon atoms, giving it a slippery texture that makes it a very effective lubricant. This slippery quality also makes graphite a good material for pencil lead because it easily sloughs off onto paper.

Covalent bond have weak intermolecular forces, that is to say, the forces between molecules is very weak. The consequence of this, is that it becomes easy to move individual molecules away from other molecules as the bonding between molecules is weak, hence it needs little energy to break. Since temperature is proportional to energy, that means the temperature required to melt the compound is low.
Thus option "A" is correct.

A covalent bond is formed between non metal atoms, which combine together by sharing electrons. covalent compounds have low melting points, do not dissolve in water, and do not conduct an electric current in solution that make them non-polar. 
Thus, Option "B" is correct.

 Covalent bonds are directional, meaning that atoms so bonded prefer specific orientations relative to one another, hence they have distinct geometries.

Covalent compounds do not show ionic reaction. 

The increasing order of forces of attraction between the molecules can be written as;
$O _{2}$(weak Van der waal forces) < HCl( dipole-dipole interactions) < $H _{2}O$( hydrogen bonding) < Hg( metallic bond) < NaCl (ionic bonding)

A solid which is transparent to visible light and whose conductivity increases with temperature is
formed by covalent bonding, like a semi conductor.

Covalent compounds have negligible forces of attraction and these are gases e.g. $HCl$, sulfur dioxide,carbon dioxide and methane. There are weak forces of attraction and such covalent substances are low boiling temperature liquids such as ethanol so boils rapidly and gives off smell.

In the above question element A is equivalent to chlorine& B to sodium thus the structure besides shows the bonding giving rise to $NaCl$ Hence for our eg, it is $BA$.

Ionic compounds are soluble in water whereas covalent compounds are insoluble in water.

Covalent bonds between atoms are quite strong, but attractions between molecule/compounds  or intermolecular forces, can be relatively weak. Covalent compounds generally have low boiling and melting points, and are found in all three physical states covalent bonds between atoms are quite strong, but attractions between molecules/compounds or intermolecular forces, can be relatively work. Covalent compounds generally have low boiling and melting points, and are found in all three physical states at room temperature. at room temperature.

A and B differ wrt type of hybridization of central atom. 'B' may have lone pair on central atom whereas 'A' has no lone pair.
'A' has dipole moment as it is trigonal planar in which individual bond dipoles cancel each other and dipole moment of 'B' is zero as it has pyramidal geometry in which individual bond dipoles do not cancel each other. 

Compound in statement 1 must be $C{ H } _{ 3 }Cl$.Since carbon,hydrogen and chlorine have different electronegativity,the bonds are polar in nature. Moreover, there is symmetry in the structure of the molecule, so there is a net dipole moment hence it is a polar molecule.

Covalent bonds are directional and ionic bonds are nondirectional. A polar bond is formed between two atoms which have different electronegativity value. The presence of polar bonds in a polyatomic molecule suggests that mostly it has non-zero dipole moment.