Test: Geometry & Shapes of Molecules - JEE MCQ

The size of SP orbital is shortest and that of SP³ is longest (SP³>SP²>SP).

The hybridisation involved in ethane is SP³, ethene is SP² and ethyne is SP

The C−C bond length is longest (1.54A^∘), C = C bond length is 1.34A^∘ .

In benzene C−C bond length is 1.39A^∘

With increase in bond enthalpy, bond length decreases.

Thus the molecule with largest bond length will have lowest bond enthalpy.

Bond order is the number of chemical bonds between a pair of atoms. For example, in diatomic nitrogen N≡N the bond order is 3, in acetylene H−C≡C−H the bond order between the two carbon atoms is also 3, and the C−H bond order is 1. Bond order gives an indication of the stability of a bond. Isoelectronic species have same bond number

Ethane has single bond, ethene has double bond, ethyne has triple bond. Hence ethyne has highest bond multiplicity.

Bond enthalpy is defined as amount of energy required to break one mole of bonds of a particular type between atoms in gaseous state.

4/2 = 2 moles

208/2 = 104 kcal 

There are 4 C-H bonds in methane.so average bond enthalpy is 1662/4=416

I₂ has a bond energy of 151 kj/mol while Cl₂ has a bond energy of 242 kj/mol. These are both non polar covalent compounds but the chlorine bond is closer to the nucleus of each of the two chlorine atoms than the iodine bond is and this makes the chlorine bond tighter and harder to break. Fluorine just happens to be a exception because it is so small. In making the bond for F₂, the electrons are forced into so small place that they tend to repel each other weakening the bond.

So the order of bond energy is   I₂222.

With increase in bond order, strength of bond increases. So the energy required to break it also increases. And so bond enthalpy increases with increase in bond order.

H-H bond will have higher Bond enthalpy because of small atomic structure.

The Bond Enthalpy or Bond Energy is the is the amount of energy released when 1 mole of bonds are formed from the isolated atoms in the gaseous state or the amount of energy required to dissociate one mole of bonds present between the atoms in the gaseous molecules. It is usually expressed in units of kJ mol^-1, measured at 298 K.

Hydrogen bonding causes the collective ground state of liquid water to have an energy lower than the ground state found in single gaseous molecules. The water hydrogen bond is a weak bond, never stronger than about a twentieth of the strength of the O-H covalent bond.

Enthalpy of reaction is the difference in energy absorbed in breaking bonds in reactants and energy released when new bonds are formed in products.

Since two moles of HBr are formed in the reaction, for 1 mole 52 kJ/mol energy is required. Since energy is released during bond formation the value would be negative.

As the s character increases in the bond, it's length decreaese.Here sp has 50% s character while sp² has 33.33% s character and sp³ has 25% s character. So carbon atoms with sp hybridisation have least bond length. Therefore C≡C has least bond length.

Bond angle refers to the angle between the two bonds i.e. the angle between twoorbitals that contains a pair of bonding electron around the central atom in a complex molecule or an ion. This angle is usually measured in degrees, further calculated using the spectroscopic method.

Bond angles are the geometrical parameters which determine the angle of each atom. 

The bond angle of NH₃ is 107°. 

The bond angle of CO₂ is 180°. 

The bond angle of CH₄ is 109.5°. 

Hence comparatively CO₂ has the maximum bond angle among these three substances.

One of the factors affecting bond enthalpy is size of atoms. Smaller is the size of bonded atoms, stronger is the bond. Consequently larger is the value of bond dissociation enthalpy. Since size of I is largest its bond enthalpy will be least.

In compound X, all the bond angles are exactly 109^∘28′X is carbon tetrachloride.
CCl has sp³ - hybridization with 4 bond pairs and 0 lone pairs of electrons giving regular tetrahedron geometry as all the four C−Cl bonds are equivalent. In others the geometry is little distorted inspite of sp³ - hybridization due to different atoms on the vertices of tetrahedron.

Bond length decreases with increase in bond multiplicity. In C₂H₄ and C₆H₆ there exists double bond. In C₂H₂ triple bond exists. In C₂H₄Br₂ single bond exists.

One of the factors affecting bond length is size of atoms.

Bond length increases with increase in size of atoms.

Since size of F is smallest out of Cl, Br and I, H-F bond will have smallest bond length.

The NH₃ molecular geometry (molecular shape) is trigonal pyramidal. The NH₃ bond angles are 107 degrees because the hydrogen atoms are repelled by the lone pair of electrons on the Nitrogen atom.