Lead is a basic metal and almost 11 isotopes of Lead are reported. The isotopes with greater natural abundance are as follow;
1) ²⁰⁸Pb with abundance 52.4 %
2) ²⁰⁶Pb with abundance 24.1 %
3) ²⁰⁷Pb with abundance 22.1 %
4) ²⁰⁴Pb with abundance 1.4 %
Molar mass of ²⁰⁸Pb:
Molar mass of any element is the total of number of protons, neutrons and electrons.
As, number of protons in Lead are 82 then in ²⁰⁸Pb isotope number of neutrons are...
# of Neutrons = M.mass - # of protons
# of Neutrons = 208 - 82
# of Neutrons = 126
Result:
Molecular Mass of Lead (²⁰⁸Pb) is 208 amu.
# of Protons in ²⁰⁸Pb = 82
# of Neutrons in ²⁰⁸Pb = 126
The average kinetic energy and rms speed of N₂ molecules at STP is
and 
Given,

The average kinetic energy of a molecule is given by,
where k is the Boltzmann constant and Tis the absolute temperature of the gas.


The rms speed of
molecules is given by

The average kinetic energy of a gas's particles is inversely related to its temperature. As the gas warms, the particles must travel more quickly since their mass is constant.
The average kinetic energy (K) is equal to one half of the mass (m) of each gas molecule times the RMS speed (vrms) squared.
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Answer: d. the distance between two rarefactions,
Explanation:
Wavelength is the distance between two identical adjacent points in a wave. This means that it is the distance between two adjacent compressions or two adjacent rarefactions.
Wavelengths are inversely related to frequency because the longer the wavelength, the less the number of wave cycles per second.
It matters to the aerodynamics of it because sometimes it's good to have the weight but only if it can take it.