I believe in what USA was and is able to achieve, and trust the nation in many but every ways. What really made it a developed nation is the things that happened in the last 3 Centuries, some of which are;
#1 CULTURAL TOLERANCE & IMMERSION
#2 TECHNOLOGICAL INVENTIONS & ADVANCEMENT IN THE FIELD OF SCIENCE
#3 FAST FOOD CULTURE
#4 HOLLYWOOD
#5 INTEGRITY & PATRIOTISM
#6 MASS CONSUMERISM
The answer should be; 11
The atomic mass number is found by combining the number of protons and neutrons
Hope this helps :)
<span>differences in the physical properties of the mixture's components</span>
<u>Answer:</u> The longest wavelength of light is 656.5 nm
<u>Explanation:</u>
For the longest wavelength, the transition should be from n to n+1, where: n = lower energy level
To calculate the wavelength of light, we use Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 
= Higher energy level = 
= Lower energy level = 2 (Balmer series)
Putting the values in above equation, we get:

Converting this into nanometers, we use the conversion factor:

So, 
Hence, the longest wavelength of light is 656.5 nm