Observation consists of receiving knowledge of the outside world through our senses,or recording information using scientific tools and instruments.Any data recorded during an experiment can be called and observation.
Answer:

Explanation:
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In this case, according to the given chemical reaction, it possible for us to set up the expression for the calculation of the enthalpy change as shown below:

Thus, given the values of the enthalpies of formation on the attached file, we obtain:
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The answer for the problem is explained below.
The option for the answer is "D".
<u><em>Therefore the energy of the light is 4.25 × 10^-19 J</em></u>
Explanation:
Given:
wavelength (λ) = 468 nm = 468×10^-9 m
speed of light (c) = 3.00 x 10^8m/s
Planck's constant is 6.626 x 10^-34J·s
To solve:
energy of light (E)
We know,
E =(h×c) ÷ λ
E = ( 6.626 x 10^-34 × 3.00 x 10^8) ÷ 468×10^-9
E = 4.25 × 10^-19 J
<u><em>Therefore the energy of the light is 4.25 × 10^-19 J</em></u>
Answer:
sorry but I don't understand Spanish
otherwise I will definitely helps you
A chemical element is a substance that is made up of only one kind atom.