How many structural isomers can you draw for pentane?

Butanone is a four-carbon compound with the functional group

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?

What is hydrogenation? What is its industrial application?

Draw the electron dot structures for
$(a)$ propanone
$(b)$ $F_2$

Explain the mechanism of the cleaning action of soaps.