Identify the invalid name for the given compound: $CH_3-CH=CH-CN$.

The $IUPAC$ name of the following hydrocarbon $(X)$ is:

Write $IUPAC$ names and calculate the number of $\sigma$ and $\pi$ bonds for the following compounds:
$(i)$ $CH_3-CH(CH_3)-CH=CH-CH_2-CH=C(CH_3)-CH_2-CH_3$
$(ii)$ $CH_3-CH=CH-CH_2-CH=CH-CH(C_2H_5)-CH_2-CH_3$
$(iii)$ $CH_2=C(CH_2-CH_2-CH_3)_2$
$(iv)$ $CH_3-CH(C_4H_9)-CH=C(C_2H_5)-CH_2-CH(CH_3)_2$

Select the structure with the correct numbering for the $IUPAC$ name of the compound.

Give the correct $IUPAC$ name for the following structure:

The $IUPAC$ name of $CH_3-CH(OH)-CH(OH)-CH(CH_3)-CHO$ is