<span>To calculate the average mass of the element, we take the summation of the product of the isotope mass and the percent abundance. In this case, it is 0.9963 * 14.003 amu + 0.0037* 15.00 amu. This is equal to an average mass of 14.00668889 amu.</span>
B; Seismometer would be the answer.
The charge on one mole of electrons = 96485 C = 1 Faraday
so if charge is 96485 C the moles of electrons are 1 = 6.023 X 10^23 electrons
if charge is 1 C the number of electrons = 6.023 X 10^23 / 96485
If charge is 50 micro C the number of electrons
= 6.023 X 10^23 X 50 X 10^-6 / 96485
= 3.12 X 10^14 electrons
Check dams shouldn't be more than 2-3 feet high. The center of it should be at least six inches lower than the edges. They might kill grass linings in channels if water stays high or sediment load is great. That criteria induces a weir effect, which makes water surface levels go upstream for some, if not all flow conditions.
Hope this helps! :)