Which of the following bases is the WEAKEST? The base is followed by its Kb value. Which of the following bases is the WEAKEST? The base is followed by its Kb value. (CH3CH2)3N, 5.2 × 10-4 C5H5N, 1.7 × 10-9 NH3, 1.76 × 10-5 HOCH2CH2NH2, 3.2 × 10-5 Since these are all weak bases, they have the same strength.

C₅H₅N is weakest base due to it's lowest Kb values.

Explanation:

Basic strength of an organic base is directly proportional with Kb(base dissociation constant) value.

Since Pyridine (C₅H₅N) is weakest base due to its lowest Kb value.

The reason of low basicity are as follows

1) lone pair containing orbital of nitrogen is sp² hybridised which is more electronegative as compare to sp³ orbital.

2) The conjuagte acid of pyridine is least stable as compare to other conjugate acids of corresponding bases.

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >