What is a pure substance that is present before a reaction but not after.

Who is better, messi or cristiano, i need this for a chemistry class. asap

Which reason best explains why metals are malleable? a)because they have delocalized electrons b)because they have localized electrons c)because they have ionic bonds d)because they have rigid bonds

A2.5% (by mass) solution concentration signifies that there is a 2.5 % (by mass) solution concentration signifies that there is blank of solute in every 100 g of solution. of solute in every 100 g of solution