They fuse helium into carbon. Hope it helped
How do seed plants protect their embryos?
Reptilian embryos are protected from desiccation by a leathery shell. Similarly, sporophytes of both gymnosperms and angiosperms protect embryos within, and they also protect male gametophytes against desiccation using .....
If you’re given molecular weight, you know that density is mass/volume. You need to convert the molecular weight to volume. If you know what molecule it is, use the gram formula mass to convert it into grams.