U8.1 Study Guide (Counting by Weighing)
Quiz by Aaron Holley
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- Q1
The weighted average mass of the different isotopes that make up a naturally occurring element is known as the __________.
average weight
average mass number
atomic mass
average atomic number
30s - Q2
The unit used for atomic mass is the ____.
atomic mass unit
numerical equivalent
atomic mass number
atomic number
30s - Q3
The atomic mass unit is defined as ____ the mass of a ______ atom.
1/12, carbon-12
1/2, hydrogen-2
1/12, nitrogen-14
1/12, carbon-14
30s - Q4
The atomic mass of naturally-occurring silicon is 28.086 amu, but there is no atom of silicon with this mass. Why does this happen?
Users enter free textType an Answer30s - Q5
Carbon exists primarily as two isotopes: carbon-12 (12.000 amu, 98.89%) and carbon-13 (13.004 amu, 1.11%), with very small traces of carbon-14. What is the atomic mass for naturally-occurring carbon? Type your answer two three decimal places, followed by a space and the units.
Users enter free textType an Answer300s - Q6
What method is used for the accurate determination of the mass of atoms and molecules?
mass spectrometry
NMR spectroscopy
UV/vis spectroscopy
Raman spectroscopy
300s - Q7
In mass spectrometry, particles are separated based on how their path changes when they pass through a magnetic field. Which particles are deflected the most by the magnetic field?
The lightest particles
The heaviest particles
The particles are deflected the same no matter what their mass is
Charged particles are not deflected by magnetic fields
300s - Q8
The following chart shows the stable isotopes of boron and their abundance in nature. Based on this chart, where would you predict the average atomic mass of boron to be?
closer to boron-10
there is no way to predict the average atomic mass from the chart given
exactly halfway between boron-10 and boron-11
closer to boron-11
120s - Q9
The following chart shows the stable isotopes of silicon and their abundance in nature. Based on this chart, where would you predict the average atomic mass of boron to be?
closer to silicon-29
closer to silicon-28
exactly the same as silicon-29
closer to silicon-30
120s - Q10
Neon has three naturally-occurring isotopes. Neon-20 has a mass of 20.000 amu (90.92% abundance) and neon-21 has a mass of 21.000 amu (0.26% abundance). If the atomic mass of neon is 20.179 amu, and the third isotope of neon has 8.82% abundance, what is the atomic mass of this third isotope? Type your answer to three decimal places and include the units.
Users enter free textType an Answer300s - Q11
Copper has two naturally-occurring isotopes. Copper-63 has an atomic mass of 62.92960 amu and is 69.17% of natural copper. If the atomic mass of copper-65 is 64.92779 amu, and the average atomic mass of copper is 63.546 amu, what is the percentage of copper-65 in nature. Type your answer to two decimal places and be sure to put the percent sign.
Users enter free textType an Answer300s - Q12
The sum of all the atomic masses of all the elements that make up a substance is called the ____.
atomic mass
molar mass
formula mass
weight of the formula
300s - Q13
What is the formula mass for lithium oxide?
29.881 amu
29.881 g/mol
22.94 amu
38.939 amu
300s - Q14
What is the formula mass for barium phosphide?
168.304 amu
88.984 amu
473.938 amu
367.582 amu
300s - Q15
What is the formula mass for cobalt(II) chloride?
94.386 amu
134.452 amu
129.839 amu
153.319 amu
300s
