To make a benzene soluble cement, `60 g` rosion is melted in an ion pot and `68 g` beeswax and `12 g` shellac are added. How much of shellac should be taken to makes `35 g` cement?

Answer

C

Explanation

`60 g "rosin" + 68 g` beeswax `+ 12 g` shellac `= 140 g` total
weight of shellac `= (35 g` total) `(12 g "shellac)/(140 g "total"))`