The most common method astronomers use to determine the composition of stars, planets, and other objects is spectroscopy. This process utilizes instruments with a grating that spreads out the light from an object by wavelength. This spread-out light is called a spectrum. Every element has a unique fingerprint that allows researchers to determine what it is made of.
The fingerprint often appears as the absorption of light. Every atom has electrons, and these electrons like to stay in their lowest-energy levels. But when photons carrying energy hit an electron, they can push it to higher energy levels. This is absorption, and each element’s electrons absorb light at specific wavelengths related to the difference between energy levels in that atom. But the electrons want to return to their original levels, so they don’t hold onto the energy for long. When they emit the energy, they release photons with exactly the same wavelengths of light that were absorbed in the first place. An electron can release this light in any direction, so most of the light is emitted in directions away from our line of sight. Therefore, a dark line appears in the spectrum at that particular wavelength.
Because the wavelengths at which absorption lines occur are unique for each element, astronomers can measure the position of the lines to determine which elements are present in a target. The amount of light that is absorbed can also provide information about how much of each element is present.
Answer:
Correc option: 
Explanation:
size of atom : it says somthing about how many shell present in a particular atom or ion and it can also be evaluated on the basis of radius of atom.
Br^- and Kr has highest number of shell as compared to other group of species .
Na ,S , Mg ,P all are from 3rd period but Kr and Br^- in the 4th period so size of species of this group will more,
Size increases on increasring the shell number
Answer : The value of 
for the given reaction is, 0.36
Explanation :
Equilibrium constant : It is defined as the equilibrium constant. It is defined as the ratio of concentration of products to the concentration of reactants.
The equilibrium expression for the reaction is determined by multiplying the concentrations of products and divided by the concentrations of the reactants and each concentration is raised to the power that is equal to the coefficient in the balanced reaction.
As we know that the concentrations of pure solids and liquids are constant that is they do not change. Thus, they are not included in the equilibrium expression.
The given equilibrium reaction is,
The expression of will be,
![K_c=\frac{[BrCl]^2}{[Br_2][Cl_2]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5BBrCl%5D%5E2%7D%7B%5BBr_2%5D%5BCl_2%5D%7D)
First we have to calculate the concentration of 
.
Now we have to calculate the value of for the given reaction.
Therefore, the value of for the given reaction is, 0.36
Answer:
Empirical formula is C3H3O
Molecular formula C9H9O3
Explanation:
From the question given, we obtained the following data:
Carbon = 63.15%
Hydrogen = 5.30%
Oxygen = 31.55%
We can obtain the empirical and molecular formula by doing the following as illustrated in the attached file. Please see attachment for explanation.
The answer would be c as the cart is not in motion therefor ruling out kinetic and it is completely at rest making all of it energy potential
