Answer: The average atomic mass of oxygen is 15.999 amu
Explanation:
Mass of isotope O-16 = 15.995 amu
% abundance of isotope O-16= 99.759 % = 
Mass of isotope O-17 = 16.995 amu
% abundance of isotope O-17 = 0.037% = 
Mass of isotope O-18 = 17.999 amu
% abundance of isotope O-18 = 0.204% = 
Formula used for average atomic mass of an element :
![A=\sum[(15.995\times 0.99759)+(16.995\times 0.00037)+(17.999 \times 0.00204)]](https://tex.z-dn.net/?f=A%3D%5Csum%5B%2815.995%5Ctimes%200.99759%29%2B%2816.995%5Ctimes%200.00037%29%2B%2817.999%20%5Ctimes%200.00204%29%5D)
Thus the average atomic mass of oxygen is 15.999 amu
The answer is unrestrained hair.
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The lines occurring in an emission spectrum are all electromagnetic waves, which means that their speed in a vacuum is
3 x 10⁸ m/s
We can use the equation,
v = fλ
which relates the velocity of a wave to the frequency and wavelength. Substituting values,
3 x 10⁸ = f * 434 x 10⁻⁹
f = 6.91 x 10¹⁴ Hz
The frequency of the wave will be 6.91 x 10¹⁴ oscillations per second.
Exothermic reaction = the term exothermic process describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light, electricity,
Endothermic reaction = An endothermic process is any process with an increase in the enthalpy H (or internal energy U) of the system. In such a process, a closed system usually absorbs thermal energy from its surroundings, which is heat transfer into the system.
