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1

### AIPMT 2010 Mains

Which of the following species is not electrophilic in nature?
A
$$\mathop C\limits^ + l$$
B
BH3
C
H3$$\mathop O\limits^ +$$
D
$$\mathop N\limits^ +$$O2

## Explanation

H3$$\mathop O\limits^ +$$ has a lone pair of electrons on oxygen atom, thus it is not an electrophile. Also the octet is complete
2

### AIPMT 2010 Prelims

Which one of the following is most reactive towards electrophilic reagent?
A
B
C
D

## Explanation

+R effect of -OH group is greater than of -OCH3 group. That is why it is highly reactive towards electrophilic substitutions.
3

### AIPMT 2009

The IUPAC name of the compound having the formula
CH$$\equiv$$C$$-$$CH$$=$$CH2 is
A
1-butyne-3-ene
B
but-1-yne-3-ene
C
1-butene-3-yne
D
3-butene-1-yne.

## Explanation

Since the sum of numbers starting from either side of the carbon chain turns out to be the same, so lowest number is given to the C = C end.
4

### AIPMT 2008

The stability of carbanions in the following.

is in the order of
A
(iv) > (ii) > (iii) > (i)
B
(i) > (iii) > (ii) > (iv)
C
(i) > (ii) > (iii) > (iv)
D
(ii) > (iii) > (iv) > (i)

## Explanation

The carbonion which have more s-character will be more stable. Thus, the order of stability is :

(i) > (ii) > (iii) > (iv)

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