(Science)
Pls help due by tmr night and I still have like 30 more questions ​

What are the percent by mass of copper in penny lab

This chart lists four kinds of polymers and their sources. what can be known about all four polymers, despite their differences? they come from living things. they share ionic carbon bonds. they are at least 100 monomers long. they are made of repeating subunits.

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: