5. What are the main differences between graphite and lead?
The text mentions some differences between graphite and lead. For example, graphite writes not only darker than lead but also softer and more breakable than lead. Moreover, lead is a material heavier than graphite therefore is more difficult to use.
6. Which do you think are the reasons for the popularity of pencils as writing instruments?
From my point of view pencils have changed our way of writing, hence is one of the most popular and materials used. In addition to help us in our day by day to take notes and write things to rebember in another time. I think that pencil is one of the best discovery of all time.