The number of sigma ($\mathrm{\sigma }$) and pi ($\mathrm{\pi }$) bonds in pent-2-en-4-yne is:

1.  13 $\mathrm{\sigma }$ bonds and no $\mathrm{\pi }$ bond.

2.  10 $\mathrm{\sigma }$ bonds and 3 $\mathrm{\pi }$ bonds.

3.  8 $\mathrm{\sigma }$ bonds and 5 $\mathrm{\pi }$ bonds.

4.  11 $\mathrm{\sigma }$ bonds and 2 $\mathrm{\pi }$ bonds.

 When two atoms combine to form a molecule, energy is: 

The correct order of \(\mathrm{C-O}\) bond length among \(\mathrm{CO},\mathrm{CO}_3^{2-},\) and \(\mathrm{CO_2}\) is :

1. \(\mathrm{CO}_2<\mathrm{CO}_3^{2-}<\mathrm{CO} \)
2. \(\mathrm{CO}<\mathrm{CO}_3^{2-}<\mathrm{CO}_2 \)
3. \(\mathrm{CO}_3^{2-}<\mathrm{CO}_2<\mathrm{CO} \)
4. \(\mathrm{CO}<\mathrm{CO}_2<\mathrm{CO}_3^{2-}\)

The bond length can be defined as -

A compound having a metal-to-metal bond is:

1. Cupric chloride           

2. Stannous chloride

3. Mercurous chloride     

4. Mercuric chloride