Moles and Empirical

Which of the following has the highest percent nitrogen by mass?

• NH₃

• N₂H₄

• NO₂

• N₂O

What is the percent by mass of chlorine in CCl₄?

• 100

• 84.16

• 7,81

• 92.19

What is the mass of 2.89x10^24 helium atoms?

• 6.96x10^48 g

• 4.80 g

• 19.2 g

• 9.60g

Which of the following 100-g sample contains the least number of atoms?

• Magnesium

• Zinc

• Silver

• Uranium

How many hydrogen atoms in in 15.2 g of water?

• 5.09x10²³

• 1.02x10²⁴

• 274

• 547

A compound has the following percent composition: Carbon 49.48%, hydrogen 5.19%, oxygen 16.48%, nitrogen 28.85%. What is the empirical formula?

• C₄H₅N₂O

• C₃H₁₀NO

• CHN₂O

• C₈H₁₂NO₂

Which of the following molecular formulas could also be an empirical formula?

• C₆H₆

• C₄₆H₉₂O₂

• C₃₀H₅₀O

• H₂O₂

What is the molar mass of Fe₃(PO₄)₂?

• 150.82

• 55.85

• 357.48

• 100.00

Imagine you have a mole of iron atoms, a mole of copper atoms, and a mole of sodium atoms. Which contains the greatest number of atoms?

• Iron

• Copper

• Sodium

• they all contain the same number of atoms

How many moles is 3.56x10²² formula units of CaCl₂?

• 6.56

• 65.64

• 2.14x10⁴⁶

• 5.91x10^-2