NTA Abhyas JEE Main2020ChemistryChemical Bonding and Molecular StructurePractice
H 2 , L i 2 , B 2 each has bond order equal to 1, the order of their stability is
Options
- AH 2 = L i 2 = B 2
- BH 2 > L i 2 > B 2
- CH 2 > B 2 > L i 2
- DB 2 > L i 2 > H 2
Correct answer
C. H 2 > B 2 > L i 2
Step-by-step solution
H 2 , L i 2 , B 2 are not equally stable. Li atom is much larger in size than H-atom. The bond order in L i 2 is much larger than bond length in H 2 . Moreover, L i 2 molecule has two electrons in the antibonding molecular orbital while H 2 has no electrons in the antiobinding molecular orbital. Thus, L i 2 is less sable than H 2 (Bond energy of Li 2 = 110 kJ mol − 2 + Bond energy of H 2 = 438 kJ mol − 1 ) Boron atom is smaller than lithium atom but larger than hydrogen atom. The B 2 is more stable than L i 2 but l