AP Chemistry - AP Classroom
Unit 1 Progress Check: MCQ
Review | Questions & Answers |
Grade A+| (Latest 2026/ 2027
Update) 100% Correct (Verified
Solutions)
Which of the following numerical expressions gives the number of
moles in 5.0g of CaO? - 5.0g ÷ 56 g/mol
WHY?
Dividing the mass of the sample by the molar mass of CaO gives the
number of moles of CaO in the sample.
In a lab a student is given a 21g sample of pure Cu metal. Which of the
following pieces of information is most useful for determining the
number of Cu atoms in the sample? Assume that the pressure and
temperature in the lab are 1.0atm and 25°C. - The molar mass of
Cu
WHY?
, By dividing the mass of the sample by the molar mass of Cu, the
number of moles of Cu in the sample can be calculated. A simple
multiplication of that number with Avogadro's number will provide the
desired information.
A 1.0mol sample of which of the following compounds has the greatest
mass? - N2O5
WHY?
The mass of a sample of any compound can be calculated by n×M,
where n is the number of moles of molecules in the sample and M is
the molar mass (mass per mole) of the compound. The compound with
molecules containing the greatest number of atoms of N and O has the
greatest molar mass. Since each sample contains the same number of
molecules (1.0mol of molecules), the sample of N2O5 has the largest
mass.
The mass spectrum for an unknown element is shown above. According
to the information in the spectrum, the atomic mass of the unknown
element is closest to - 91 amu
WHY?
The relative abundances of the isotopes with atomic masses 90 and 92
have a weighted average that would be less than 91. That result with
the influence of the mass and abundance of the isotope with atomic
mass 94 would result in a weighted average closer to 91 than to 93.
Unit 1 Progress Check: MCQ
Review | Questions & Answers |
Grade A+| (Latest 2026/ 2027
Update) 100% Correct (Verified
Solutions)
Which of the following numerical expressions gives the number of
moles in 5.0g of CaO? - 5.0g ÷ 56 g/mol
WHY?
Dividing the mass of the sample by the molar mass of CaO gives the
number of moles of CaO in the sample.
In a lab a student is given a 21g sample of pure Cu metal. Which of the
following pieces of information is most useful for determining the
number of Cu atoms in the sample? Assume that the pressure and
temperature in the lab are 1.0atm and 25°C. - The molar mass of
Cu
WHY?
, By dividing the mass of the sample by the molar mass of Cu, the
number of moles of Cu in the sample can be calculated. A simple
multiplication of that number with Avogadro's number will provide the
desired information.
A 1.0mol sample of which of the following compounds has the greatest
mass? - N2O5
WHY?
The mass of a sample of any compound can be calculated by n×M,
where n is the number of moles of molecules in the sample and M is
the molar mass (mass per mole) of the compound. The compound with
molecules containing the greatest number of atoms of N and O has the
greatest molar mass. Since each sample contains the same number of
molecules (1.0mol of molecules), the sample of N2O5 has the largest
mass.
The mass spectrum for an unknown element is shown above. According
to the information in the spectrum, the atomic mass of the unknown
element is closest to - 91 amu
WHY?
The relative abundances of the isotopes with atomic masses 90 and 92
have a weighted average that would be less than 91. That result with
the influence of the mass and abundance of the isotope with atomic
mass 94 would result in a weighted average closer to 91 than to 93.
