Test: Geometry And Shapes Of Molecules


20 Questions MCQ Test Chemistry Class 11 | Test: Geometry And Shapes Of Molecules


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This mock test of Test: Geometry And Shapes Of Molecules for Class 11 helps you for every Class 11 entrance exam. This contains 20 Multiple Choice Questions for Class 11 Test: Geometry And Shapes Of Molecules (mcq) to study with solutions a complete question bank. The solved questions answers in this Test: Geometry And Shapes Of Molecules quiz give you a good mix of easy questions and tough questions. Class 11 students definitely take this Test: Geometry And Shapes Of Molecules exercise for a better result in the exam. You can find other Test: Geometry And Shapes Of Molecules extra questions, long questions & short questions for Class 11 on EduRev as well by searching above.
QUESTION: 1

 Molecule in which the distance between two adjacent carbon atom is largest, is:

Solution:

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

QUESTION: 2

 The bond length in hypothetical molecules A2, B2, C2 and D2 are given. Which of the following will have lowest bond enthalpy?

Solution:

With increase in bond enthalpy, bond length decreases.

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

QUESTION: 3

Bond order for N2 molecule is​

Solution:

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

QUESTION: 4

Amongst the following molecules, the one with the highest bond multiplicity is:

Solution:

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

QUESTION: 5

Energy required to dissociate 4g of gaseous hydrogen into free gaseous atoms is 208 kcal at 25°C . The bond energy of H-H bond will be:

Solution:

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 

QUESTION: 6

 Energy required to break all four C-H bonds in methane is 1662 kJ/mol. Calculate the average bond enthalpy for methane molecule.

Solution:

There are 4 C-H bonds in methane.so average bond enthalpy is1662/4=416

QUESTION: 7

 Among the following halogens the one with highest bond energy is:

Solution:

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.

QUESTION: 8

Which of the following statements relating bond order and bond enthalpy are correct?

Solution:

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.

QUESTION: 9

 Which of the following will have highest value of bond enthalpy?

Solution:

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

QUESTION: 10

 Generally unit of bond enthalpy is expressed in:

Solution:

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.

QUESTION: 11

Bond energy of covalent O-H bond in water is:

Solution:

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.

QUESTION: 12

 Use bond energies to estimate the enthalpy of formation of HBr(g).
BE(H-H) = 436 kJ/mol
BE(Br-Br) = 192 kJ/mol
BE(H-Br) = 366 kJ/mol

Solution:

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.

QUESTION: 13

Which bond among the following has the shortest bond length?

Solution:

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.

QUESTION: 14

Bond angle is the average angle between orbitals containing ___________ electron pairs around the central atom in a molecule.

Solution:

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.

QUESTION: 15

Which of the following has maximum bond angle?

Solution:

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.

QUESTION: 16

Which of the following molecules will have smallest bond enthalpy?

Solution:

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.

QUESTION: 17

 In compound X, all bond angles are exactly 109° 28’, X is:

Solution:

In compound X, all the bond angles are exactly 10928′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.

QUESTION: 18

The C-H bond distance is longest in:

Solution:

 

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.

QUESTION: 19

Which of the following molecules will have smallest bond length?

Solution:

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.

QUESTION: 20

The bond angle, H-N-H in NH3 molecule is:

Solution:

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.