One way in which Earth’s evolution as a planet can be understood is by measuring the amounts of certain isotopes in rocks. One quantity recently measured is the ratio of 129Xe to 130Xe in some minerals. In what way do these two isotopes differ from one another? In what respects are they the same?

5. A sample of Magnesium contains three isotopes and its average atomic weight is 24.35 amu. If the sample is composed of 62.10% of 2*Mg (21.92 amu), 23.30% of 2°Mg (20.92 amu). What is abundance and atomic weight of the third isotope?

There are two isotopes of the element lithium that occur naturally, 6Li (mass = 6.015 amu) and 7Li (mass = 7.016 amu). Given that the average atomic mass of lithium is 6.941 amu, what are the fractional abundances of the lithium isotopes?

There are two naturally occurring isotopes of europium, 151Eu(151.0 amu) and 153Eu(153.0 amu). If the atomic mass of Eu is 151.96, what is the approximate natural abundance of 151Eu?

Copper has two stable isotopes with the following atomic masses: copper-63 (atomic mass = 62.9296 amu) and copper-65 (atomic mass = 64.9278 amu). If the average atomic mass of copper is 63.546 amu, calculate the relative abundance of each isotope.

The element copper has two naturally occurring isotopes with masses of 62.9400 amu and 64.9300 amu. What would be the percent abundance of the second isotope, if the atomic weight were 63.9522 amu?

Gallium is a metal which forms compounds with a wide variety of uses. Some of the applications of gallium compounds include computer memory chips, light emitting diodes and lasers. Radioactive isotopes of gallium are used to image the human body and locate tumors. Naturally occurring gallium consists of two isotopes. One of those isotopes is 71Ga with an isotopic mass of 70.9247050 amu and an abundance of 39.892%. What is the mass number of the other isotope?

There are four isotopes of strontium. They have mass number of 84, 86,87 and 33. The atomic mass of strontium is 87.62 amu. What does it say about the relative abundance of isotopes?

Gallium is a metal which forms compounds with a wide variety of uses. Some of the applications of gallium compounds include computer memory chips, light emitting diodes and lasers. Radioactive isotopes of gallium are used to image the human body and locate tumors. Naturally occurring gallium consists of two isotopes. One of those isotopes is 71Ga with an isotopic mass of 70.9247050 amu and an abundance of 39.892%. What is the mass number of the other isotope?

An unmanned space shuttle mission brings samples back to Earth from Mars.  Working with samples from mars, you discover that the isotope abundances on Mars are different from on Earth.  You are tasked with calculating the average atomic mass (weight) of nitrogen that exists naturally on Mars.  You find that the abundance of nitrogen-15 (atomic mass of  15.000 amu) on Mars is 11.639%, and the rest of the nitrogen (abundance = 100% - 11.639%) is nitrogen-14 (atomic mass 14.003 amu).  Using that information, what is the average atomic mass (in amu) of nitrogen on Mars? (answer should have 3 decimal places - only input numbers, not "amu")