The correct order of –I effect is:

1. -NR₃⁺ > -OR  > -F

2. -F > -NR₃⁺ > -OR  

3.-NR₃⁺ > -F  > -OR  

4. -OR  > -NR₃⁺ > -F

Polarisation of electrons in acrolein may be written as:

1.  $\stackrel{+\delta }{C}{H}_2=CH-\stackrel{-\delta }{C}HO$

2.  $\stackrel{-\delta }{C}{H}_2=CH-\stackrel{+\delta }{C}HO$

3.  $\stackrel{-\delta }{C}{H}_2=CH-\stackrel{}{C}\stackrel{+\delta }{H}O$

4.  $\stackrel{+\delta }{C}{H}_2=CH-CH\stackrel{-\delta }{O}$

The correct order of stability is:

Which amongst the following is the most stable carbocation:
 

1.		2.
3.		4.