Which are characteristics of electromagnetic waves?

Helium decays to form lithium. which equation correctly describes this decay?

Concentrations expressed as a percent by mass are useful when the solute is a a. liquid b. gas c. solid

Will mark as brainliest ! how many grams of iron metal do you expect to be produced when 245 grams of an 80.5 percent by mass iron (ii) nitrate solution react with excess aluminum metal? show all work needed to solve this problem!