Answer:
Valence Electrons
Explanation:
Valence electrons are the electrons in the outermost shell and can be used to form bonds.
Answer : The final equilibrium temperature of the water and iron is, 537.12 K
Explanation :
In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.


where,
= specific heat of iron = 560 J/(kg.K)
= specific heat of water = 4186 J/(kg.K)
= mass of iron = 825 g
= mass of water = 40 g
= final temperature of water and iron = ?
= initial temperature of iron = 
= initial temperature of water = 
Now put all the given values in the above formula, we get:


Therefore, the final equilibrium temperature of the water and iron is, 537.12 K
First, we will get the number of moles:
one mole contains Avogadro's number of atoms. Therefore, to know the number of moles in <span>7.83 × 10^24 atoms, we will simply do cross multiplication as follows:
number of moles = (</span><span>7.83 × 10^24*1) / (6.022 * 10^23) = 13 moles
From the periodic table:
mass of one mole of helium = 4 grams
Therefore:
mass of 13 moles of helium = 13*4 = 52 grams</span>
If you have a concern about fluoride in your drinking water, you can get more information by contacting the local community water system and is denoted as option D.
<h3>What is Water?</h3>
This is referred to as a universal solvent and is usually colorless and used for various purposes such as drinking, washing etc.
Fluoride is added to water by the the community water system as it helkps to build strong teeth and cavities thereby preventing tooth decay. They know the concentration which is added to the water which is why they need to be contacted for more information.
Read more about Water here brainly.com/question/5060579
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