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Consider the two beakers labeled A and B. Beaker A contains 1 mole of iron atoms, and Beaker B contains 1 mole of lead atoms. Which statement concerning these samples is known with certainty?

Calculate the number of moles of BaF 2 in a 10.0 g sample of BaF 2.

Consider the following precipitation reaction. Which of the following correctly identifies the spectator ions in this reaction? Na 2S( aq) + CuSO 4( aq) → Na 2SO 4( aq) + CuS( s)

When solutions of sodium sulfide and copper(II) sulfate are mixed, a precipitate of copper(II) sulfide is formed. What is the net ionic equation for this reaction?

The mass of one atom of oxygen is 16.00 amu. What is the mass of one mole of elemental oxygen (O 2)?

What is the mass of 4.00 moles of helium, the gas commonly used to fill party balloons and lighter-than-air ships?

How is the reaction shown below best classified? 2HgO(s) → 2Hg(l) + O 2(g)

Which notation properly indicates how two molecules of diatomic oxygen would be represented in a chemical equation?

How is the reaction shown below best classified? 2NaCl(s) + F2(g) → 2NaF(s) + Cl2(g)

The chemical equation below is unbalanced. What is the coefficient of water when the equation is balanced? Mg(OH) 2( s) + HCl( g) → MgCl 2( s) + H 2O( l)