Question

Low barrier H-bonds:

		require the distance between heteroatoms to be larger than for a normal H-bond
		redistribute electron density in the reactive intermediate and accomplish rate acceleration by hydrogen tunneling
		require the pKas for the two heteroatoms to be different
		have energies of 60 kJ/mol or more because the energy barrier the H atom must surmount to exchange heteroatoms becomes greater as the distance between hetroatoms decreases

Answer 1

correct answers :

1) redistribute electron density in the reactive intermediate and accomplish rate acceleration by hydrogen tunneling

2) have energies of 60 kJ/mol or more because the energy barrier the H atom must surmount to exchange heteroatoms becomes greater as the distance between hetroatoms decreases

why remaining two wrong statements :

LBHB require the pKas for the two heteroatoms to be matched or almost same

require the distance between heteroatoms to be shorter than for a normal H-bond