Moles, Percent Composition, Empirical/Molecular Formula Retest

What is the percent by mass of sodium in NaCl?

• 39%
• 61%
• 35%
• 65%

Which pair has the same empirical formula?

• NaCrO₄ and Na₂Cr₂O₇
• C₂H₄O₂ and C₆H₁₂O₆
• C₃H₆O₃ and C₂H₆O₂
• CH₄ and C₂H₆

A compound consists of 72.2% magnesium(Mg) and 27.8% nitrogen(N) by mass. What is the empirical formula?

• Mg₄N₃
• MgN₂
• Mg₃N₂ 
• MgN

Given the following: 42.07% Na, 18.89% P, and 39.04% O, determine the empirical formula.

•  NaPO2
• Na2PO3
• Na3PO4
• NaPO4

How many molecules of sugar (C₆H₁₂O₆) are in a mole?

• 24 molecules
• 180 molecules
• 180 g
• 6.02 x 10²³ molecules

How many moles are in 3.01 x 10²² atoms of magnesium?

• 0.05 moles
• 1.81 x 10⁴⁶ moles
• 5.00 x 10²¹ moles
• 5 moles

What is the mass of 0.89 mol of CaCl₂?

• 111 grams
• 0.008 grams
• 98.9 grams
• none of the choices

(0901) How many water molecules are in 5.2 moles of water?

• 6.0 x 10²³ molecules

• 5.2 molecules

• 3.1 x 10²⁴ molecules

• 8.6 x 10^-24 molecules

What is the molecular formula if the empirical formula is CH₂O and the molecular molar mass is 180.18?

• CH₂O
• C₂H₄O₂
• C₄H₈O₄
• C₆H₁₂O₆

What is the molecular formula for a compound with the empirical formula: K₂SO₄ and a molecular mass of 696g.

• K₂SO₄ 
• K₈SO₁₆
• K₈S₄O₈ 
• K₈S₄O₁₆