We are given –
- Mass of
is 57.1 g and we are asked to find number of moles present in 57.1 g of 






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Now,Let's calculate the number of moles present in 57.1 g of 






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Number 1 is Comets and asteroids
Number 2 is Comets are made of ice and rock
Number 3 is Meteor
Answer: The atomic weight of silver is 107.87 amu
Explanation:
Mass of isotope silver-107 = 106.91 amu
% abundance of isotope silver -107 = 51.84% = 
Mass of isotope silver-109 = 108.90 amu
% abundance of isotope silver-109 = 48.16% = 
Formula used for average atomic mass of an element :

![A=\sum[(106.91\times 0.5184)+(108.90\times 0.4816)]](https://tex.z-dn.net/?f=A%3D%5Csum%5B%28106.91%5Ctimes%200.5184%29%2B%28108.90%5Ctimes%200.4816%29%5D)

Thus atomic weight of silver is 107.87 amu
I believe the answer would be halogens