Q.

The correct order of decreasing acidity of the following aliphatic acids is             [2025]
 

1 HCOOH>CH3COOH>(CH3)2CHCOOH>(CH3)3CCOOH  
2 HCOOH>(CH3)3CCOOH>(CH3)2CHCOOH>CH3COOH  
3 (CH3)3CCOOH>(CH3)2CHCOOH>CH3COOH>HCOOH  
4 CH3COOH>(CH3)2CHCOOH>(CH3)3CCOOH>HCOOH  

Ans.

(1)

Acidic strength -I effect 1+I effect. Electron donating groups decrease the stability of carboxylate ion. Thus, the correct order of decreasing acidity is 
HCOOH>CH3COOH>(CH3)2CHCOOH>(CH3)3CCOOH.