Stoichiometry ASASI

Which statement correctly describes the relationship between relative atomic mass and isotopic mass?

• Relative atomic mass is always equal to the mass number of the isotope.
• Relative atomic mass is the average of isotopic masses weighted by their abundance.
• Isotopic mass is calculated based on Avogadro's number.
• Relative atomic mass and isotopic mass are always identical.

Given two isotopes of chlorine: Cl-35 (75%) and Cl-37 (25%), what is the relative atomic mass?

• 35.00
• 35.25
• 35.50
• 36.25

What is the mass of 0.5 mol of Al2O3 (molar mass = 102 g/mol)?

• 51 g
• 102 g
• 204 g
• 25.5 g

How many atoms are in 3.0 mol of CO2?

• 6.022 x 10^23
• 1.807 x 10^24
• 3.0 x 10^23
• 5.432 x 10^24

Determine the empirical formula of a compound with 40% C, 6.7% H, and 53.3% O.

• CH2O
• C2H4O2
• C3H8O
• C6H12O6

Which compound has the empirical formula CH2O and a molar mass of 180 g/mol?

• C6H12O6
• C2H4O2
• C3H6O3
• CH2O

A gas occupies 44.8 dm³ at STP. How many moles of the gas are present?

• 1 mol
• 2 mol
• 0.5 mol
• 3 mol

What is the percent composition of nitrogen in NH3?

• 82.35%
• 75.00%
• 17.65%
• 14.00%

What volume will 3 mol of gas occupy at STP?

• 22.4 dm³
• 44.8 dm³
• 67.2 dm³
• 33.6 dm³

What is the empirical formula of a compound formed from 3.6 g of C and 0.6 g of H?

• CH
• C2H2
• CH2
• C3H6