Chapter 3 (Upgrade Yourself)

How many atoms are contained in 25 g of NaBr? (Atomic mass of Na = 23, Br = 35)

• 102.96 molecules

• 0.24 molecules

• 1.45x10²³ molecules

• 2.34 x 10²⁰molecules

Identify the number of Chlorine atoms in 65.8 g CaCl_2.

• 7.14 x 10²³ atoms

• 8.71 x 10²³ atoms

• 1.22 x 10²³ atoms

• 3.57 x 10²³ atoms

How many molecules are in 2.00 moles of H₂O?

• 124x10²⁴ molecules of H₂O
• 1.20x10²³ molecules of H₂O
• 1.20x10²⁴ molecules H₂O
• 124

How many grams are in 1.2 x 10²⁴ molecules of CO? (molar mass of CO = 28 g/mol)

• 28.2 g

• 55.8 g

• 6.02 g

• 1.2 g

A student needs 65.0 g of copper(II) chloride for an experiment. How many atoms of copper is this?

• 2.91 x 10^23 atoms

• 3.91 x 10^25 atoms

• 2.35 x 10^23 atoms

• 4.70 x 10^23 atoms

A mole of Neon contains
6.02 x 10²³ _____.

• atoms
• formula units
• ions
• molecules

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

• 0.0500 moles
• 1.81 x 10⁴⁶ moles
• 5.00 x 10²¹ moles
• 5.00 moles

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

• Mg₄N₃
• MgN₂
• Mg₃N₂ 
• MgN

Which of the following is considered an empirical formula?

• CH₃COOH
• C₆H₁₂O₆
• H₂O

How many molecules are in 2.5 mol of NaCl?

• 1.5 x 10²⁴ molecules

• 1.5 molecules

• 4.15 molecules

• 1.5 x 10²³ molecules