Answer:
When the excited electron fall back to the lower energy levels the energy is released in the form of radiations.The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum
Explanation:
The electron is jumped into higher level and back into lower level by absorbing and releasing the energy.
The process is called excitation and de-excitation.
Excitation:
When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits. For example if electron jumped from K to L it must absorbed the energy which is equal the energy difference of these two level. The excited electron thus move back to lower energy level which is K by releasing the energy because electron can not stay longer in higher energy level and comes to ground state.
De-excitation:
When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum
The given balanced reaction is,

The stoichiometric coefficients of each element or compound represents the number of moles of that element or compound required for the complete reaction to take place.
The mole ratios of different products and reactants will be:



So the mole ratio comparing iron (Fe) and oxygen gas (
) is
4 : 3
The patch area in square kilometers is 1.59*10⁻⁹ km₂
Why?
This is an unit conversion problem. We have to convert from cm² to km². We can do that by knowing that there are 100 cm in 1 m, and 1000 m in 1 km, so 100000 cm=1km. Knowing that we can apply the following conversion factor:

Now to convert this value to scientific notation, we have to move the decimal point to the right until we get a whole number, and the exponent of the number 10 is going to be the number of spaces we moved to the right (negative), so the final answer is:

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Atomic mass!!! the electrons and atomic mass will always be the same most the time
Answer: The cells that make up the digestive, muscular, skeletal, reproductive, and excretory systems all need oxygen from the respiratory system to function, and the cells of the respiratory system—as well as all the other systems—need nutrients and must get rid of metabolic wastes.
Explanation: