Even though nitrogen in ammonia is in ${\mathrm{sp}}^3$-hybridisation, the bond angle deviate from ${109}^{°}{28}^{}$. Explain.

Which hybrid orbitals are used by carbon atoms in the following molecule?

${\mathrm{CH}}_3-{\mathrm{CH}}_3$

Which hybrid orbitals are used by carbon atoms in the following molecule?

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

Which hybrid orbitals are used by carbon atoms in the following molecule?

${\mathrm{CH}}_3-{\mathrm{CH}}_2-\mathrm{OH}$