Molecular Orbital Theory (MOT) — Practice Questions

Free NEET Chemistry multiple-choice questions on Molecular Orbital Theory (MOT). Attempt each question and reveal the answer with a full explanation.

According to Molecular Orbital Theory, the molecule He 2 does not exist because: Its bond order is zero It is diamagnetic It is highly reactive It has only bonding electrons Which of the following diatomic molecular species is diamagnetic and has the shortest bond length? N 2 O 2 C 2 B 2 According to Molecular Orbital Theory, the paramagnetic nature of the Oxygen molecule ( O 2 ) is explained by the presence of unpaired electrons in: Ï€ 2p orbitals Ï€ 2p orbitals σ 2p orbitals σ 2p orbitals The bond order of the CO molecule is 3. What is the bond order of the CN - ion? 3 2.5 2 3.5 In which of the following molecules is the bond order of the C-O bond approximately 1.33 ? CO 3 2- CO 2 CO CH 3OH The paramagnetic nature of the NO 2 molecule is due to: The presence of an odd number of valence electrons p -d back bonding Its bent molecular geometry The presence of coordinate covalent bonds The correct order in which the O-O bond length increases in the following is :- O3 < H2O2 < O2 O2 < O3 < H2O2 O2 < H2O2 < O3 H2O2 < O2 < O3 The correct order of C - O bond length among CO, CO3 2- , CO2 is CO < CO3 2- < CO2 CO3 2- < CO2 < CO CO < CO2 < CO3 2- CO2 < CO3 2- < CO Identify a molecule which does not exist. Li2 C2 O2 He2 Given below are two statements : Statement I : A hypothetical diatomic molecule with bond order zero is quite stable. Statement II : As bond order increases, the bond length increases. In the light of the above statements, choose the most appropriate answer from the options given below : Statement I is false but Statement II is true Both Statement I and Statement II are true Both Statement I and Statement II are false Statement I is true but Statement II is false Identify the correct order of bond order for the following oxygen species: O 2 + > O 2 > O 2 - > O 2 2- O 2 2- > O 2 - > O 2 > O 2 + O 2 > O 2 + > O 2 - > O 2 2- O 2 + > O 2 - > O 2 > O 2 2- Which of the following is paramagnetic? O 2 N 2 F 2 CN - The pair of species that has the same bond order is: CO and NO + O 2 and B 2 N 2 and O 2 NO and CO The correct order of stability for H 2, H 2 + and H 2 - is: H 2 > H 2 + > H 2 - H 2 > H 2 - > H 2 + H 2 + > H 2 - > H 2 H 2 - > H 2 + > H 2 Using MO theory, predict which of the following species has the shortest bond length? O 2 2+ O 2 + O 2 - O 2 2- The bond order of P-O bond in phosphate ion ( PO 4 3- ) is: 1.25 1.0 1.33 1.5 The correct order of bond strength for O 2, O 2 +, O 2 - and O 2 2- is: O 2 + > O 2 > O 2 - > O 2 2- O 2 2- > O 2 - > O 2 > O 2 + O 2 > O 2 + > O 2 - > O 2 2- O 2 + > O 2 - > O 2 > O 2 2- The molecular orbital electronic configuration of O 2 2- ion is: 1s 2 1s 2 2s 2 2s 2 2p z 2 ( 2p x 2 = 2p y 2) ( 2p x 2 = 2p y 2 ) 1s 2 1s 2 2s 2 2s 2 2p z 2 ( 2p x 2 = 2p y 2) ( 2p x 1 = 2p y 1 ) 1s 2 1s 2 2s 2 2s 2 ( 2p x 2 = 2p y 2) 2p z 2 1s 2 1s 2 2s 2 2s 2 2p z 2 ( 2p x 2 = 2p y 2) Which of the following is correct regarding the bond order and magnetism of O 2 2- ? Bond order = 1, Diamagnetic Bond order = 1, Paramagnetic Bond order = 1.5, Paramagnetic Bond order = 2, Diamagnetic In the vapor state, sulfur exhibits paramagnetic behavior. According to Molecular Orbital Theory, this is due to the presence of two unpaired electrons in: Ï€ antibonding orbitals Ï€ bonding orbitals σ antibonding orbitals σ bonding orbitals According to Molecular Orbital Theory, the bond order and magnetic nature of the N 2 2- ion are: 2 and Paramagnetic 2.5 and Diamagnetic 2 and Diamagnetic 1.5 and Paramagnetic The bond order of N 2 2+ is the same as that of: O 2 N 2 O 2 2+ C 2 Which of the following statements is FALSE regarding the CO molecule? The bond order is 2.5. It is a polar molecule. It is isoelectronic with N 2 . It acts as a strong ligand in coordination chemistry. When O 2 reacts with AsF 5 , the compound [O 2] +[AsF 6] - is formed. In this process: The O-O bond length decreases The O-O bond length increases The magnetic behavior changes from paramagnetic to diamagnetic The bond order remains the same Which of the following is true for the Nitric Oxide ( NO ) molecule? It is paramagnetic in the gaseous state It is diamagnetic in the gaseous state It has a bond order of 3 It follows the octet rule for all atoms Which of the following diatomic molecular species has a bond order of 2.5 and is paramagnetic? NO N 2 + O 2 + CN Arrange the following in increasing order of N-N bond length: N 2, N 2H 2, N 2H 4 . N 2 < N 2H 2 < N 2H 4 N 2H 4 < N 2H 2 < N 2 N 2 < N 2H 4 < N 2H 2 N 2H 2 < N 2 < N 2H 4 According to Molecular Orbital Theory, the C 2 molecule has: Only bonds Only bonds One and one bond Two and one bond Which of the following molecular species is paramagnetic and has a bond order of 1? B 2 C 2 N 2 Li 2 In a (antibonding) molecular orbital, the number of nodal planes perpendicular to the internuclear axis is: 1 0 2 3 Potassium superoxide ( KO 2 ) is paramagnetic because of the presence of an unpaired electron in: 2p orbital of O 2 - 2s orbital of O 2 - 2p orbital of O 2 - 2p z orbital of O 2 - What is the bond order of the C 2 2- ion? 3 2 2.5 1.5 Which of the following is the correct order of bond stability? O 2 > O 2 + > O 2 - O 2 + > O 2 > O 2 - O 2 - > O 2 > O 2 + O 2 > O 2 - > O 2 + Which of the following has the highest bond dissociation enthalpy? N 2 O 2 F 2 H 2 The correct order of C-O bond length in CO , CO 2 , and CO 3 2- is: CO < CO 2 < CO 3 2- CO 2 < CO < CO 3 2- CO 3 2- < CO 2 < CO CO < CO 3 2- < CO 2 According to Molecular Orbital Theory, the bond order of the He 2 + ion is: 0.5 1.0 0 1.5 Based on Molecular Orbital Theory, which of the following species has the highest bond order? O 2 2+ O 2 + O 2 O 2 - According to MO theory, the bond order of the Nitric Oxide ( NO ) molecule is: 2.5 2.0 3.0 1.5 Comparing N 2 and N 2 - , according to Molecular Orbital Theory: N 2 is more stable and diamagnetic N 2 - is more stable and paramagnetic Both have the same stability N 2 is paramagnetic and N 2 - is diamagnetic According to Molecular Orbital Theory, which of the following energy level sequences is correct for the N 2 molecule? 2s < 2s < ( 2p x = 2p y ) < 2p z 2s < 2s < 2p z < ( 2p x = 2p y ) 2s < 2s < ( 2p x = 2p y ) < 2p z 2s < 2s < 2p z < 2p z The species CaC 2 contains a carbon-carbon bond. According to Molecular Orbital Theory, the bond order of the C 2 2- ion in calcium carbide is: 3 2 2.5 1 Based on Molecular Orbital Theory, what happens to the bond length when N 2 is converted to N 2 + ? Increases Decreases Remains the same Bond length becomes zero The magnetic moment of O 2 is approximately 2.83 BM . This indicates that it has: 2 unpaired electrons 1 unpaired electron 3 unpaired electrons 0 unpaired electrons Which of the following species has the shortest bond length? O 2 + O 2 O 2 - O 2 2- Which of the following diatomic molecular species has the highest bond order? CO O 2 NO B 2 According to molecular orbital theory, which of the following will not be a viable molecule? He 2 2+ He 2 + H 2 - H 2 2- The bond order of 1.5 is shown by: O 2 - O 2 O 2 + O 2 2- According to MO theory which of the following lists ranks the nitrogen species in terms of increasing bond order : N 2 - < N 2 2- < N 2 N 2 - < N 2 < N 2 2- N 2 2- < N 2 - < N 2 N 2 < N 2 2- < N 2 - Which of the following is paramagnetic? CO O2 - CN - NO + Consider the following species : CN+ , CN- , NO and CN Which one of these will have the highest bond order? CN+ CN- NO CN Which of the following diatomic molecular species has only bonds according to Molecular Orbital Theory? Be2 O2 N2 C2 Which amongst the following is incorrect statement? C2 molecule has four electrons in its two degenerate molecular orbitals H2+ ion has one electron O2+ ion is diamagnetic The bond orders of O2+ , O2 , O2 - and O2 2- are 2.5, 2, 1.5 and 1, respectively The correct order of energies of molecular orbitals of N2 molecule, is 1s < 1s < 2s < 2s < ( 2p x = 2p y) < 2p z < ( 2p x = 2p y) < 2p z 1s < 1s < 2s < 2s < 2p z < ( 2p x = 2p y) < ( 2p x = 2p y) < 2p z 1s < 1s < 2s < 2s < 2p z < 2p z < ( 2p x = 2p y) < ( 2p x = 2p y) 1s < 1s < 2s < 2s < ( 2p x = 2p y) < ( 2p x = 2p y) < 2p z < 2p z Which of the following diatomic molecular species has only π bonds according to Molecular Orbital Theory? C 2 Be 2 Li 2 N 2 According to MOT, which of the following is correct for O 2 + ? Bond order is 2.5 and it is paramagnetic Bond order is 2 and it is paramagnetic Bond order is 2.5 and it is diamagnetic Bond order is 1.5 and it is paramagnetic The species CO , CN - and NO + are isoelectronic. Which of the following statements is true for these species? All have a bond order of 3 Bond order of CO is 3 while others are 2 All have different bond orders Only CN - and NO + have a bond order of 3 Which of the following diatomic molecular species is paramagnetic and has a bond order of 1? B 2 C 2 N 2 Li 2 In which of the following processes, the bond order has increased and the magnetic behaviour has changed from paramagnetic to diamagnetic? N 2 N 2 + C 2 C 2 + NO NO + O 2 O 2 + According to Molecular Orbital Theory, which of the following is true for the C 2 molecule? Both bonds are bonds. The bond order is 2 and one is , one is . The bond order is 3. The molecule is paramagnetic. In the case of B 2 molecule, which of the following molecular orbitals is filled last according to the energy level diagram (considering s-p mixing)? 2p x and 2p y 2p z 2s 2p x Which of the following statements is true for the C 2 molecule according to MO theory? It has only bonds. It is paramagnetic. The bond order is 3. It has one and one bond. According to Molecular Orbital Theory, which of the following species has a bond order of 3.5 ? CO + N 2 + O 2 + CN - How many nodal planes are present in the 2p (antibonding) molecular orbital? 2 1 0 3 What is the total number of nodal planes in the 2p z bonding molecular orbital? 0 1 2 3 Which of the following species has the highest bond order? CO + CO NO + CN - Identify the correct order of stability for the following Nitrogen species based on bond order: N 2 > N 2 + > N 2 - N 2 + > N 2 > N 2 - N 2 - > N 2 > N 2 + N 2 > N 2 - > N 2 + According to Molecular Orbital Theory, which of the following is true regarding the Be 2 molecule? Bond order is zero and it is unstable Bond order is 1 and it is stable Bond order is 2 and it is stable Bond order is 0.5 and it is unstable According to Molecular Orbital Theory, which of the following statements is true for the CO + ion? The bond order of CO + (3.5) is higher than that of CO (3.0). The bond order of CO + (2.5) is lower than that of CO (3.0). The CO + ion is diamagnetic. The electron is removed from a bonding molecular orbital. Compare the stability of N 2 + and N 2 - according to Molecular Orbital Theory. N 2 + is more stable than N 2 - . N 2 - is more stable than N 2 + . Both have equal stability as they have the same bond order. Stability cannot be predicted from bond order alone. What is the total number of antibonding electrons present in the Oxygen molecule ( O 2 ) according to Molecular Orbital Theory? 6 4 2 8 The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is:- 2 3 4 1 The highest occupied molecular orbital for Ne2 is 2p 2p 2p 2p Which one of the following species is diamagnetic? N 2 NO O 2 B 2 Which of the following diatomic molecules has the highest bond order? N 2 O 2 F 2 Li 2