A large group of stars & a dust bound together by gravity

Consider the lewis structures for the compound so3 and the polyatomic ions so32 - and so42-. which of these must exist as a set of resonance structures?

How many milligrams remain of a 15.0 mg sample of radium-226 after 6396 years? The half life of radium-226 is 1599 years.

Calculate the molecular mass of Na2HPO4

Why are elements called building blocks

Using complete sentences, explain how to predict the products and balance the reaction for the combustion of butane, C4H10. C4H10 + O2

Bacteria are only found in decaying matter. A. True B. False

Which is considered a chemical mutagen? tanning beds tobacco X-rays precious metals

Combining 0.380 mol Fe2O3 with excess carbon produced 13.7 g Fe Fe2O3 + 3C → 2Fe + 3CO What is the actual yield of iron in moles? What is the theoretical yield of iron in moles? What is the percent yield?

When a hydrogen electron makes a transition from n=3 to n=1?

If two electrons have same number of protons but different number of neutrons can they be atoms of the same element?