Number of pure $p-$ orbitals in the given molecule $\text{hexa-}1, 3-\text{dien-}5-\text{yne}$.

Amongst the given options,the compound$(s)$ in which all the atoms are in one plane in all the possible conformations (if any),is (are):
$(A)$ $CH_2=CH-CH=CH_2$
$(B)$ $HC\equiv C-CH=CH_2$
$(C)$ $H_2C=C=O$
$(D)$ $H_2C=C=CH_2$

Examine the following common chemical structures to which simple functional groups are often attached. Which of these systems have essentially planar geometry?

The total number of $C-C$ sigma $(\sigma)$ bonds in mesityl oxide $(C_6H_{10}O)$ is $......$. (Round off to the nearest integer).

Which of the following underlined carbon atoms possesses $sp$ hybridization?

Determine the hybridization of the $C_3$ and $C_6$ carbon atoms in the given structure,respectively. (Numbering starts from the left end of the longest chain containing the principal functional group).