How many structural isomers can you draw for pentane ?

What would be the electron dot structure of carbon dioxide which has the formula $CO _{2}$ ?

How would you name the following compounds ?

$(i)$ $CH _{3}- CH _{2}- Br$

$(ii)$ $\begin{matrix}
   H  \\
   |  \\
   H-C=O  \\
\end{matrix}$

$(iii)$ $\begin{matrix}
   \begin{matrix}
   H\,\,\,\,\,H\,\,\,\,\,\,\,H\,\,\,\,\,H\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\, \\
   |\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,  \\
\end{matrix}  \\
   H-C-C-C-C-C\equiv C-H  \\
   \,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,  \\
   H\,\,\,\,\,\,\,H\,\,\,\,\,\,\,H\,\,\,\,\,H\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
\end{matrix}$

People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes ?

Butanone is a four-carbon compound with the functional group