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

What is the number of $sp^3$ hybrid carbon atoms in $HO(CH_2)_3CH(CH_3)CH(CH_3)_2$?

The hybridization of carbon involved in the $C_2-C_3$ single bond in the molecule $CH \equiv C-CH=CH_2$ is

Which of the following starred carbon atoms is the most electronegative?

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

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):
$(A)$ $CH_2=CH-CH=CH_2$
$(B)$ $HC\equiv C-CH=CH_2$
$(C)$ $H_2C=C=O$
$(D)$ $H_2C=C=CH_2$