Which of the following statements about the conformers of ethane is correct?”

1.	Bond angle changes, but bond length remains the same.
2.	Both bond angle and bond length change.
3.	Both bond angle and bond length remain the same.
4.	Bond angle remains the same, but the bond length changes.

The correct order with respect to –I effect of the substituents is:
(R = alkyl)

1. –NH₂ > –OR < –F
2. –NR₂ < –OR < –F
3. –NH₂ > –OR > –F
4. –NR₂ > –OR > –F

The most stable carbocation among the following is:

1.	`	2.
3.		4.

The correct statement about the S_N1 reaction is:

Which one of the following statements is not correct for a nucleophile?

1. Nucleophile is a lewis acid.
2. Ammonia is a nucleophile.
3. Nucleophiles attack low electron density sites.
4. Nucleophiles are not electron-seeking.

Two possible stereo-structures of CH₃CHOH.COOH, that are optically active, called:

In Duma's method for estimation of nitrogen, 0.25 g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm pressure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is:

Which of the following compounds gives the most stable carbocation on ionization of its C–Cl bond?

1.		2.
3.		4.

Hyperconjugation occurs among the following compounds:

The enolic form of ethyl acetoacetate is given below:

 

The number of σ and π bonds in the enolic form are respectively:

1. 18 sigma bonds and 2 pi-bonds
2. 16 sigma bonds and 1 pi-bond
3. 9 sigma bonds and 2 pi-bonds
4. 9 sigma bonds and 1 pi-bond