Gallium has an average atomic mass of 69.72 amu and has two common isotopes 69Ga and 71Ga. If the 69Ga isotope (mass 68.926 amu) is 60.11% abundant, what is the atomic mass of the 71Ga isotope

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?

How many neutrons are in 37.0 ug ( ug= 10^-6 g) of 14 6 C? You may assume that the atomic mass of 14 6 C is exactly 14.0 U. Avogadro's number = 6.022 x10^23

b) The mass of 205TI is about 204.9744 amu. Why then does the periodic chart have an atomic weight of thallium that is different from 204.9744 amu?

Bromine has two stable isotopes: 79Br and 81Br with masses of 78.9183371 amu and 80.9162906 amu. If the average atomic mass for Bromine on Earth is 79.904 amu, what is the mass of 79Br in a 10.0 g sample? Hint: Set the abundance of the 79Br isotope equal to x. Then the abundance of the other isotope will equal 1−x. Your answer should have three significant figures, so round to the nearest hundredth.

Antimony has many uses, including infrared devices and as part of an alloy in lead storage batteries. The element has two naturally occurring isotopes, one with mass 120.904 amu, the other with mass 122.904 amu.(a) Enter the notation for each isotope.  antimony−121       antimony−123       (b) The atomic mass of antimony is 121.8 amu. Use this value to calculate the percent abundance of each isotope.    % antimony−121    % antimony−123

Silicon (average atomic mass=28.0855amu) has three isotopes. Their masses are 27.9769amu, 28.9765amu, and 29.9738amu. The abundance of the heaviest isotope is 2.96%. Estimate the abundances of the first two isotopes.

In nature, Titanium has five stable isotopes. If the atomic masses and the relative abundances for each of the first three isotopes are respectively, the mass of the fifth isotope will be:  the mass of the fourth isotope is 48. 948 amu and its abundance is 5.5% 46Ti=45.953 uma and 8.0%, 47Ti=46.952 uma and 7.3%, 48Ti=47.948 uma and 73.8%