Which of the following species contains an equal number of $\mathrm{\sigma }$ and $\mathrm{\pi }$ bonds?

1. ${\mathrm{HCO}}_3^{-}$

2. ${\mathrm{XeO}}_4$

3. ${\left(\mathrm{CN}\right)}_2$

4. CH₂(CN)₂

Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has a high melting point?

1. Metallic bonding

2. Van der Waals' bonding

3. Ionic bonding

4. Covalent bonding

What is the dominant intermolecular force or bond that must be overcome in converting liquid CH₃OH to a gas?

1. Hydrogen bonding

2. Dipole-dipole interaction

3. Covalent bonds

4. London dispersion force

The correct order of C-O bond length among CO, ${\mathrm{CO}}_3^{2-}$ , CO₂ is:

1. $C{O}_2<C{O}_3^{2-}<CO$

2. $CO<C{O}_3^{2-}<C{O}_2$

3. $C{O}_3^{2-}<C{O}_2<CO$

4. $CO<C{O}_2<C{O}_3^{2-}$