Iron carbonyl, $\mathrm{Fe}{\left(\mathrm{CO}\right)}_5$, is classified as:

1.	Tetranuclear	2.	Mononuclear
3.	Trinuclear	4.	Dinuclear

Match  Column-I with Column-II and mark the most appropriate option:

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 molecule among the following that has the hybridization ${\mathrm{sp}}^2,\hspace{0.17em}{\mathrm{sp}}^2,\hspace{0.17em}\mathrm{sp},\; and\hspace{0.17em}\mathrm{sp}$ from left to right atoms is:

1. $\mathrm{HC}\equiv \mathrm{C}-\mathrm{C}\equiv \mathrm{H}$

2. ${\mathrm{CH}}_2=\mathrm{CH}-\mathrm{C}\equiv \mathrm{CH}$

3. ${\mathrm{CH}}_2=\mathrm{CH}-\mathrm{CH}={\mathrm{CH}}_2$ 

4. ${\mathrm{CH}}_2-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_3$

The experimental proof for semiconservative replication of DNA was first shown in a:

1. Fungus

2. Bacterium

3. Plant

4. Virus

Offsets are produced by: