Why is elemental zinc considered a pure substance ?

Why did southern business leaders want to increase the number of slaves

In a reaction (at equilibrium) that makes more moles of gas than it consumes, what is the effect of increasing the pressure?

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.