empirical and molecular formulas

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

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 empirical formula if you have 81.82% carbon and 18.18% hydrogen?

• C3H8
• CH4
• C2H2
• C4H10

Glycerol has a molar mass of 92.09g/mol. Its percent composition is: 39.12% C, 8.75% H, and 51.12% O. What is the molecular formula for glycerol?

• C₂H₃O₂
• CH₂O
• C₂H₄O₂
• C₃H₈O₃

Tags

NGSS.HS-PS1-1

True or False: One mole of Sulfur has 2.35 x 10¹⁴ atoms.

• True

• False

Tags

NGSS.HS-PS1-7

How many moles are in 50 grams of Calcium Bromide, CaBr₂?

• 0.75

• 1.25

• 0.25

• 0.55

Tags

NGSS.HS-PS1-7

If I have 6.02 x10²³ molecules of CO₂, what is the mass?

• 44.0 g
• 2.65 x10²³ g
• 1.37 x10²² g
• 96.0 g

Tags

NGSS.HS-PS1-7

What is the volume of 0.5 mol C₃H₈ gas at STP?

• 0.0335 L

• 11.2 L

• 16.8 L

• 22.4 L

What is the percent by mass of oxygen in MgO?

• 20%
• 40%
• 50%
• 60%